Mechanical feedthroughs for implantable medical device

ABSTRACT

An implantable medical device assembly comprises a sealed housing; a motor including a rotating output shaft within the sealed housing; a first coaxial shaft within the sealed housing, the first coaxial shaft being mechanically coupled to the rotating output shaft such that rotation of the rotating output shaft drives rotation of the first coaxial shaft; a second coaxial shaft external to the sealed housing, the second coaxial shaft being in axial alignment with the first coaxial shaft; an oscillating component mechanically coupling the first coaxial shaft to the second coaxial shaft, wherein rotation of the rotating first coaxial shaft drives the oscillation of the oscillating component, wherein the oscillation of the oscillating component drives rotation of the second coaxial shaft; and a flexible seal including the oscillating component. The sealed housing and the flexible seal combine to form a substantially sealed enclosure encasing the motor and the first coaxial shaft.

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/035,765, filed Aug. 11, 2014, U.S. ProvisionalPatent Application Ser. No. 62/035,776, filed Aug. 11, 2014, U.S.Provisional Patent Application Ser. No. 62/035,843, filed Aug. 11, 2014,and U.S. Provisional Patent Application Ser. No. 62/035,862, filed Aug.11, 2014. The entire contents of each of these applications areincorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to medical devices and, moreparticularly, to medical leads configured for delivering electricalstimulation therapy and/or sensing electrical physiological signals.

BACKGROUND

Implantable electrical stimulators may be used to deliver electricalstimulation therapy to patients to treat a variety of symptoms orconditions such as chronic pain, tremor, Parkinson's disease, epilepsy,urinary or fecal incontinence, sexual dysfunction, obesity, orgastroparesis. In general, an implantable stimulator deliversneurostimulation therapy in the form of electrical pulses. Animplantable stimulator may deliver neurostimulation therapy via one ormore medical leads that include electrodes located proximate to targettissues of the brain, the spinal cord, pelvic nerves, peripheral nerves,or the stomach of a patient. Hence, stimulation may be used in differenttherapeutic applications, such as deep brain stimulation (DBS), spinalcord stimulation (SCS), pelvic stimulation, gastric stimulation, orperipheral nerve stimulation. Stimulation also may be used for musclestimulation, such as functional electrical stimulation (FES) to promotemuscle movement or prevent atrophy.

Stimulation therapy may be more effective with accurate placement of themedical leads within the targeted region of a patient, such as thebrain, central nervous system or urological tract for example. Medicalleads may incorporate anchoring systems to passively hold medical leadsin place once positioned by a clinician during an implantationprocedure. However, occurrences of misplaced or dislodged leads maystill impact clinical outcomes for some patients, and may even requiresurgical repositioning of implanted medical leads. Surgicalrepositioning of misplaced or dislodged leads causes increased risks,discomfort and inconvenience for patients and consumes additionalhealthcare resources.

SUMMARY

This disclosure includes techniques associated with the design,manufacture and use of mechanically adjustable medical leads. Techniquesas described herein may facilitate post-surgical mechanicalrepositioning of medical lead electrodes. Disclosed techniques includelead designs, mechanical feedthrough designs as well as techniques foruse and manufacture of the same. Some disclosed techniques, such asmechanical feedthrough designs, have applicability well beyond medicalleads. Disclosed mechanical feedthrough designs may be also used withother medical devices to simultaneously provide torque transmission andhermetic isolation between chambers of an implantable medical device.This would enable implantable device therapy options requiring thetransmission of torque across a hermetic boundary.

In one example, this disclosure is directed to an implantable medicaldevice assembly comprising: a sealed housing; a motor within the sealedhousing, the motor including a rotating output shaft; a first coaxialshaft within the sealed housing, the first coaxial shaft beingmechanically coupled to the rotating output shaft such that rotation ofthe rotating output shaft drives rotation of the first coaxial shaft; asecond coaxial shaft external to the sealed housing, the second coaxialshaft being in axial alignment with the first coaxial shaft; anoscillating component mechanically coupling the first coaxial shaft tothe second coaxial shaft, wherein rotation of the rotating first coaxialshaft drives the oscillation of the oscillating component, wherein theoscillation of the oscillating component drives rotation of the secondcoaxial shaft; and a flexible seal including the oscillating component,wherein the sealed housing and the flexible seal combine to form asubstantially sealed enclosure encasing the motor and the first coaxialshaft.

In another example, this disclosure is directed to a method of adjustinga mechanically adjustable medical lead. The mechanically adjustablemedical lead includes an electrode and a rotatable member, the rotatablemember being mechanically coupled to the electrode. The method comprisesoperating a motor within a hermetically sealed enclosure to drive therotatable member of the medical lead and move a position of theelectrode to adjust a spacing between a proximal end of the medical leadand the electrode.

The details of the present disclosure are set forth in the accompanyingdrawings and the description below. Other features, objects, andbenefits of the present disclosure will be apparent from the descriptionand drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating an example stimulationsystem with a mechanically adjustable medical lead implanted in thebrain of a patient.

FIG. 2 is a functional block diagram of an example implantable medicaldevice that generates electrical stimulation pulses.

FIG. 3 is a functional block diagram of an example programmer for animplantable medical device.

FIGS. 4A-4C illustrate a mechanically adjustable medical lead.

FIG. 5 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient.

FIG. 6 is a cross-sectional view of a mechanically adjustable medicallead including a force sensor configured to measure a resistance tomovement of a position of an electrode of the medical lead.

FIG. 7 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient based on a signal from a force sensor.

FIGS. 8A and 8B illustrate cross-sectional views of a mechanicallyadjustable medical lead including a retractable electrode.

FIG. 9 is a flowchart illustrating an example technique for deploying aretractable electrode of a mechanically adjustable medical leadimplanted within a patient.

FIGS. 10A-10D illustrate components of a nutating mechanical feedthroughthat facilitates mechanical coupling to a rotating shaft within ahermetically sealed enclosure.

FIG. 11 is a conceptual diagram of an assembly including a motor withina hermetically sealed enclosure and a nutating mechanical feedthroughthat facilitates mechanical coupling to a rotating shaft of the motor.

FIG. 12 is a flowchart illustrating an example technique for operating amotor within a hermetically sealed enclosure to adjust a spacing betweena proximal end of a medical lead and an electrode of the medical lead.

FIG. 13 is a flowchart illustrating an example technique formanufacturing a nutating mechanical feedthrough that facilitatesmechanical coupling to a rotating shaft within a hermetically sealedenclosure.

FIG. 14 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient based on a physiological condition of thepatient.

FIG. 15 illustrates an assembly including a motor and a mechanicalfeedthrough with a pair of coaxial shafts coupled with an offset pin andsealed with a flexible seal including an oscillating cap, the offset pinand the oscillating cap being fixed relative to one another as afunctionally unitary component.

FIG. 16 illustrates an assembly including a motor and a mechanicalfeedthrough with a pair of coaxial shafts coupled with an offset pin andsealed with a flexible seal including an oscillating cap, the offset pinand the second shaft outside the sealed housing being fixed relative toone another as a functionally unitary component.

FIG. 17 illustrates an assembly including a motor and a mechanicalfeedthrough with a pair of coaxial shafts coupled with an offset pin andsealed with a flexible seal including an oscillating cap, the offset pinand the second shaft within the sealed housing being fixed relative toone another as a functionally unitary component.

FIG. 18 is a flowchart illustrating an example technique formanufacturing a mechanical feedthrough that facilitates mechanicalcoupling to a rotating shaft within a hermetically sealed enclosure.

DETAILED DESCRIPTION

Techniques as disclosed herein may permit clinicians administeringtherapy via medical leads to reposition one or more electrodes of animplanted medical lead in a non-invasive manner. Techniques as disclosedherein may facilitate post-surgical (e.g., post-implantation) mechanicalrepositioning of medical lead electrodes. Such techniques may be used toachieve improved therapy outcomes by permitting repositioning whilelimiting the incidence of additional surgical procedures among patientsas well as potentially providing a higher level of electrode placementprecision for all patients.

As one example, the disclosed techniques may limit the need for surgicalrepositioning as well as facilitate medical lead implantation withinjuvenile patients who are still growing. For example, juvenile dystoniapatients and others with fast-growing brains and skulls, who mightotherwise benefit from DBS therapy, may not currently be candidates toreceive the therapy as repeated neurosurgical procedures may be requiredto account for patient growth over time.

Furthermore, post-surgical mechanical repositioning of medical leadelectrodes may allow more precise electrode positioning than positioningonly via surgical means. For example, cannulation error and limitationson surgical dexterity may impose inherent limits on the positioningaccuracy and precision of electrodes on medical leads during animplantation procedure.

FIG. 1 is a conceptual diagram illustrating an example stimulationsystem with a mechanically adjustable medical lead implanted in thebrain of a patient. As shown in FIG. 1, stimulation system 10 includesimplantable medical device (IMD) 20 and mechanically adjustable medicallead 14 implanted within patient 12. Specifically, mechanicallyadjustable medical lead 14 enters through cranium 16 and is implantedwithin brain 18 to deliver deep brain stimulation (DBS). One or moreelectrodes of mechanically adjustable medical lead 14 provideselectrical pulses to surrounding anatomical regions of brain 18 in atherapy that may alleviate a condition of patient 12.

Mechanically adjustable medical lead 14 includes medical lead body 24with electrodes 21, motor 15 and screw mechanism 17. Mechanicallyadjustable medical lead 14 also may include optional force sensor 23,which is configured to measure a resistance to movement of mechanicallyadjustable medical lead 14. In some examples, more than one mechanicallyadjustable medical leads may be implanted within brain 18 of patient 12to stimulate multiple anatomical regions of the brain. As shown in FIG.1, system 10 may also include a programmer 19, which may be a handhelddevice, portable computer, or workstation that provides a user interfaceto a clinician. The clinician interacts with the user interface toprogram stimulation parameters and optionally to non-invasively adjustthe positioning of one or more electrodes of mechanically adjustablemedical lead 14.

DBS may be used to treat dysfunctional neuronal activity in the brainthat manifests as diseases or disorders such as Huntington's disease,Parkinson's disease, or movement disorders. Symptoms of these diseasescan be lessened or eliminated with electrical stimulation therapy.Certain anatomical regions of brain 18 are responsible for producing thesymptoms of such brain disorders. As one example, stimulating ananatomical region, such as the Substantia Nigra, in brain 18 may reducethe number and magnitude of tremors experienced by patient 12. Otheranatomical regions may include the subthalamic nucleus, globus pallidusinterna, ventral intermediate, and zona inserta. Anatomical regions suchas these are targeted by the clinician during mechanically adjustablemedical lead 14 implantation. In other words, the clinician may attemptto position the medical lead as close to these regions as possible.

The clinician interacts with the user interface to manually select andprogram certain electrodes of mechanically adjustable medical lead 14and adjust the resulting stimulation field with the anatomical regionsas guides, or define one or more stimulation fields only affectanatomical regions of interest. Once the clinician has defined the oneor more stimulation fields, system 10 automatically generates thestimulation parameters associated with each of the stimulation fieldsand transmits the parameters to IMD 20.

The stimulation field defined by the clinician using a user interfacedescribed herein is associated with certain stimulation parametervalues. Programmer 19 generates the stimulation parameters required bythe stimulation field and wirelessly transmits the parameters to IMD 20.The parameters may be generated automatically or based on manualselection by a patient or clinician user. The parameters may also besaved on programmer 19 for review at a later time. In some cases,programmer 19 may not be capable of generating stimulation parametersthat can produce the defined stimulation field within brain 18.Programmer 19 may display an error message to the clinician alerting theclinician to adjust the stimulation field. Programmer 19 may alsodisplay a reason why the stimulation field cannot be provided, such asthe field is too large or an electrode is malfunctioning and cannot beused. Other errors may also be displayed to the clinician.

Generally, the user interface is not used to provide real-timeprogramming to IMD 20. The clinician will use the user interface todefine stimulation fields, and programmer 19 automatically generates thestimulation parameters when the clinician has determined the stimulationfield is ready for therapy. In this manner, stimulation therapyperceived by patient 12 does not change at the same time the clinicianchanges the stimulation field. However, the user interface could be usedas such in a real-time programming environment to provide immediatefeedback to the clinician.

System 10 may also include multiple medical leads 14 or electrodes onmedical leads of other shapes and sizes. The user interface may allowthe clinician to program each medical lead simultaneously or require theclinician to program each medical lead separately. In some DBS patients,two medical leads 14 are implanted at symmetrical locations within brain18 for bilateral stimulation. In particular, a first medical lead isplaced in the right hemisphere of brain 18 and a second medical lead isplaced at the same location within the left hemisphere of the brain.Programmer 19 may allow the clinician to create a stimulation field forthe first medical lead and create a mirrored stimulation field for thesecond medical lead. The clinician may be able to make fine adjustmentto either stimulation field to accommodate the slight anatomical regiondifferences between the left and right hemispheres.

While mechanically adjustable medical lead 14 is described for use inDBS applications as an example, mechanically adjustable medical lead 14,or other medical leads, may be implanted at any other location withinpatient 12. For example, mechanically adjustable medical lead 14 may beimplanted near the spinal cord, pudendal nerve, sacral nerve, or anyother nervous or muscle tissue that may be stimulated. The userinterface described herein may be used to program the stimulationparameters of any type of stimulation therapy. Therapy may also bechanged if medical leads migrate to new locations within the tissue orpatient 12 no longer perceives therapeutic effects of the stimulation.

As mentioned above, mechanically adjustable medical lead 14 includesmotor 15 and screw mechanism 17, which facilitates the non-invasivelyrepositioning of one or more of electrodes 21. In one example, motor 15may include one or more reversible, high-resolution, stepper-motors todrive screw mechanism 17 based in power and/or control signals from IMD20. In the same or different examples, screw mechanism 17 may includefine-pitch threaded screws that facilitate altering the overall lengthof medical lead 14, adjusting the spacing or “pitch” between electrodes21, angular displacement of electrodes 21, radial displacement from theaxis-of-insertion of electrodes 21, and/or other electrode positioningparameters of medical lead 14.

System 10 may employ “active-positioning” of electrodes 21 of medicallead 14. For example, system 10 may monitor a physiological condition ofthe patient based on the positioning of electrodes 21 in order todetermine a precise desired positioning of electrodes 21. In the same ordifferent examples, system 10 may monitor physiological conditions ofpatient 12 actively or passively via electrodes 21 at differentpositions of electrodes 21. Therapy parameters may include positionsettings and different stimulation and/or sensing therapy parameter setsmay have different, and even unique, prescribed position settings. Inthe same or different examples, system 10 may actively adapt positionsettings according to monitored physiological parameters of patient 12,for example, to achieve improved efficacy of a stimulation treatment viaelectrodes 21 or improved sensing via electrodes 21.

In some examples, system 10 may monitor a force signal representing theresistance to movement of the position of the electrode(s) from forcesensor 23 and repositioning of electrodes of medical lead 14 may bebased on the resistance to movement of the position of the electrodes asindicated by force sensor 23. In some examples, force sensor 23 mayinclude a piezoelectric sensor. In the same or different examples, forcesensor 23 may include a current sensor and force may be measured bymonitoring current required to operate motor 15. In one particularexample, system 10 may limit movement of the position of electrodes 21to prevent the resistance to movement of the position of the electrodefrom exceeding a predefined value.

FIG. 2 is a functional block diagram of an example implantable medicaldevice that generates electrical stimulation signals. In the example ofFIG. 2, IMD 20 includes a processor 70, memory 72, stimulation generator74, telemetry interface 76, and power source 78. As shown in FIG. 2,stimulation generator 74 is coupled to mechanically adjustable medicallead 14. Alternatively, stimulation generator 74 may be coupled to adifferent number of medical leads as needed to provide stimulationtherapy to patient 12. Each lead 14 may include one, two, or moreelectrodes that are coupled to stimulation generator 74 via respectiveconductors within the lead.

Processor 70 controls stimulation generator 74 to deliver electricalstimulation therapy according to programs generated by a user interfaceand stored in memory 72 and/or received from programmer 19 via telemetryinterface 76. As an example, a new program received from programmer 19may modify the electrode configuration and amplitude of stimulation.Processor 70 may communicate with stimulation generator 74 to change theelectrode configuration used during the therapy and modify the amplitudeof stimulation. Processor 70 may then store these values in memory 72 tocontinue providing stimulation according to the new program. Processor70 may stop the previous program before starting the new stimulationprogram as received from programmer 19. In some examples, intensity ofthe stimulation signal may be ramped down or ramped up as a program isbeing turned off or turned on. In this manner, no abrupt stimulationchanges may be perceived by patient 12. Intensity may be controlled, forexample, by varying one or more of voltage or current amplitude, pulsewidth and/or pulse frequency. A ramp up of the new program may providepatient 12 time to stop stimulation if the new program is uncomfortable.

Processor 70 may comprise any one or more of a microprocessor, digitalsignal processor (DSP), application specific integrated circuit (ASIC),field-programmable gate array (FPGA), or other digital logic circuitry.Memory 72 stores instructions for execution by processor 70, forexample, instructions that when executed by processor 70 cause theprocessor and IMD to provide the functionality ascribed to them herein,as well as stimulation programs. Memory 72 may include any one or moreof a random access memory (RAM), read-only memory (ROM),electronically-erasable programmable ROM (EEPROM), flash memory, or thelike.

Stimulation generator 74 may provide stimulation in the form of pulsesto patient 12. Alternatively, stimulation generator 74 may providetherapy in the form of some continuous signal such as a sine wave orother non-pulse therapy. Stimulation parameters for each stimulationprogram may include electrode configuration, current or voltageamplitude, pulse width, pulse rate, and/or duty cycle. Other parametersmay be used depending on the therapy to be provided to patient 12.Stimulation generator 74 may independently utilize any of electrodes 21.In this manner, stimulation generator 74 may be utilized to deliverstimulation via numerous different electrode configurations to providetherapy for a wide variety of patient conditions. In addition,stimulation generator 74 may test the functionality of electrodes onmechanically adjustable medical lead 14. Based upon the impedancetesting, specific electrodes may be removed from possible use in therapywhen the test indicates that the impedance is above or below normaloperating limits.

An electrode combination is a selected subset of one or more electrodeslocated on one or more implantable medical leads coupled to animplantable stimulator. The electrode combination also refers to thepolarities of the electrode segments in the selected subset. Theelectrode combination, electrode polarities, voltage or currentamplitude, pulse width and pulse rate together define a program fordelivery of electrical stimulation therapy by an implantable stimulatorvia an implantable medical lead or medical leads. By selectingparticular electrode combinations, including selected electrodes andpolarities, a physician can target particular anatomic structures. Byselecting values for amplitude, pulse width and pulse rate, thephysician can attempt to optimize the electrical therapy delivered tothe patient via the selected electrode combination or combinations.

In general, a clinician selects values for a number of programmableparameters in order to define the electrical stimulation therapy to bedelivered by the implantable stimulator to a patient. For example, theclinician ordinarily selects a combination of electrodes carried by oneor more implantable medical leads, and assigns polarities to theselected electrodes. In addition, the clinician selects an amplitude,which may be a current or voltage amplitude, a pulse width and a pulserate for stimulation pulses to be delivered to the patient. A group ofparameters, including electrode combination, electrode polarity,amplitude, pulse width and pulse rate, may be referred to as a programin the sense that they drive the neurostimulation therapy to bedelivered to the patient. In some applications, an implantablestimulator may deliver stimulation therapy according to multipleprograms either simultaneously or on a time-interleaved, overlapping ornon-overlapping, basis.

A clinician may further select positioning parameters for electrodes ofmedical lead 14. For example, the clinician may employ“active-positioning” of electrodes 21 of medical lead 14 in whichprocessor 70 monitors a physiological condition of the patient based onthe positioning of electrodes 21 in order to determine a precise desiredpositioning of electrodes 21. In the same or different examples,processor 70 may monitor physiological conditions of patient 12 activelyor passively via electrodes 21 at different positions of electrodes 21.Therapy parameters may include position settings and differentstimulation and/or sensing therapy parameter sets may have different,even unique, prescribed position settings.

In some examples, a clinician may select positioning parameters based onthe resistance to movement of the position of the electrode(s) fromforce sensor 23 and repositioning of electrodes of medical lead 14 maybe based on the resistance to movement of the position of the electrodesas indicated by force sensor 23. In one particular example, a clinicianmay select parameters to limit movement of the position of electrodes 21to prevent the resistance to movement of the position of the electrodefrom exceeding a predefined value.

In the same or different examples, a clinician may select positioningparameters based on a monitored physiological condition of the patient.For example, electrodes 21 may be used to monitor electrical signalslike brain activity, and whereby the system responds to those signals bymechanically moving/repositioning itself in a manner that helps toenhance the detection of such signals, and thus help to optimize thesignal/noise ratio of the detection function, and or optimize thedelivery of the corresponding therapeutic signal that is generated inresponse to the detected signal. The positioning parameters mayrepresent a closed-loop response to monitored physiological conditionsof the patient.

Telemetry interface 76 may include circuitry known in the art forfacilitating wireless telemetry, for example, via radio frequency (RF)communication or proximal inductive interaction with similar circuitrywithin external programmer 19. Power source 78 delivers operating powerto the components of IMD 20. Power source 78 may include a battery and apower generation circuit to produce the operating power. In someexamples, the battery may be rechargeable to allow extended operation.Recharging may be accomplished through proximal inductive interactionbetween an external charger and an inductive charging coil within IMD20. In other examples, non-rechargeable batteries may be used. As afurther alternative, an external power supply could transcutaneouslypower IMD 20 whenever stimulation is needed or desired.

FIG. 3 is a functional block diagram of an example programmer. As shownin FIG. 3, external programmer 19 includes processor 80, memory 82, userinterface 84, telemetry interface 86, and power source 88. Programmer 19may be used to present anatomical regions to the user via user interface84, select stimulation programs, generate new stimulation programs withstimulation fields, and transmit the new programs to IMD 20. Asdescribed herein, programmer 19 may allow a clinician to definestimulation fields and generate appropriate stimulation parameters. Forexample, as described herein, processor 80 may store stimulationparameters as one or more programs in memory 82. Processor 80 may sendprograms to IMD 20 via telemetry interface 86 to control stimulationautomatically and/or as directed by the user.

Programmer 19 may be one of a clinician programmer or a patientprogrammer in some examples, i.e., the programmer may be configured foruse depending on the intended user. A clinician programmer may includemore functionality than the patient programmer. For example, a clinicianprogrammer may include a more featured user interface, to allow aclinician to download usage and status information from IMD 20, andallow a clinician to control aspects of the IMD not accessible by apatient programmer example of programmer 19.

A user, either a clinician or patient 12, may interact with processor 80through user interface 84. User interface 84 may include a display, suchas a liquid crystal display (LCD), light-emitting diode (LED) display,or other screen, to show information related to stimulation therapy, andbuttons or a pad to provide input to programmer 19. Buttons may includean on/off switch, plus and minus buttons to zoom in or out or navigatethrough options, a select button to pick or store an input, and pointingdevice, i.e. a mouse, trackball, pointstick or stylus. Other inputdevices may be a wheel to scroll through options or a touch pad to movea pointing device on the display. In some examples, the display may be atouch screen that enables the user to select options directly from thedisplay screen.

Processor 80 processes instructions from memory 82 and may store userinput received through user interface 84 into the memory whenappropriate for the current therapy. In addition, processor 80 providesand supports any of the functionality described herein with respect toeach example of user interface 84. Processor 80 may comprise any one ormore of a microprocessor, digital signal processor (DSP), applicationspecific integrated circuit (ASIC), field-programmable gate array(FPGA), or other digital logic circuitry.

Memory 82 may include instructions for operating user interface 84,telemetry interface 86 and managing power source 88. Memory 82 alsoincludes instructions for generating stimulation fields and stimulationparameters from the stimulation fields. These instructions may include aset of equations needed to characterize brain tissue and interpretstimulation field dimensions. Memory 82 may include any one or more of arandom access memory (RAM), read-only memory (ROM),electronically-erasable programmable ROM (EEPROM), flash memory, or thelike. Processor 80 may comprise any one or more of a microprocessor,digital signal processor (DSP), application specific integrated circuit(ASIC), field-programmable gate array (FPGA), or other digital logiccircuitry.

Memory 82 may store program instructions that, when executed byprocessor 80, cause the processor and programmer 19 to provide thefunctionality ascribed to them herein. For example, memory 82 mayinclude a plurality of stimulation templates that are used by processor80 to create a stimulation template set. Memory 82 may also includeinstructions for generating stimulation parameters based upon thedefined stimulation field. In addition, instructions that allowprocessor 80 to create electrical field models and activation fieldmodels may be stored within memory 82. An atlas or reference anatomicalregion may also be stored in memory 82 for presentation to theclinician. In some examples, memory 82 does not contain instructions forall functionality for the user interfaces and programming of stimulationparameters as described herein. In this case, memory 82 may only holdthe necessary instructions for the specific example that the userdesires. Memory 82 may be reformatted with different sets ofinstructions when needed.

Wireless telemetry in programmer 19 may be accomplished by radiofrequency (RF) communication or proximal inductive interaction ofprogrammer 19 with IMD 20. This wireless communication is possiblethrough the use of telemetry interface 86. Accordingly, telemetryinterface 86 may include circuitry known in the art for suchcommunication.

Power source 88 delivers operating power to the components of programmer19. Power source 88 may include a battery and a power generation circuitto produce the operating power. In some examples, the battery may berechargeable to allow extended operation. Recharging may be accomplishedthrough proximal inductive interaction, or electrical contact withcircuitry of a base or recharging station. In other examples, primarybatteries may be used.

FIGS. 4A-4C illustrate mechanically adjustable medical lead 100, whichmay be utilized as a DBS lead and may, for example, correspond tomechanically adjustable medical lead 14 of FIG. 1. In particular, FIG.4A is a cross-sectional view of mechanically adjustable medical lead100. FIG. 4B is a close-up view of proximal end 101 of mechanicallyadjustable medical lead 100, and FIG. 4C illustrates motor assembly 130Bof mechanically adjustable medical lead 100. In other examples, medicallead 100 may be utilized for other sensing and or simulation of anytissue of a patient, including, but not limited to, spinal cordstimulation and sensing, peripheral nerve stimulation and sensing,pelvic nerve stimulation and sensing, gastric nerve stimulation andsensing, vagal nerve stimulation and sensing, stimulation and sensing ofmuscles or muscle groups, stimulation and sensing of an organ such asgastric system stimulation and sensing, stimulation and sensingconcomitant to gene therapy and others.

Proximal end 101 of medical lead 100 may be coupled to an IMD (forexample, IMD 20 of FIG. 1) via one or more conductive wires, such as ina lead extension (not shown). Medical lead 100 includes a medical leadbody 102 and electrodes 104 and 105. Medical lead body 102 may have asubstantially circular cross-sectional shape, but other shapes may alsobe used. Medical lead body 102 may be formed from an insulativebiocompatible material. Exemplary biocompatible material includes atleast one covers of polyurethane, silicone, and fluoropolymers such astetrafluroethylene (ETFE), polytetrafluroethylene (PTFE), and/orexpanded PTFE (i.e. porous ePTFE, nonporous ePTFE). Electrodes 104 and105 are exposed to tissue of the patient, which allows physiologicalsignals to be sensed from the tissue and/or therapy delivered to thepatient.

Electrode 105 is located at a distal portion of medical lead body 102,whereas electrode 104 is located more proximally along medical lead body102 as compared to electrode 105. As shown in FIG. 4, electrodes 104 and105 are ring electrodes extending substantially around the entireperiphery, for example, circumference, of medical lead 100. In otherexamples, instead of or in addition to electrodes 104 and 105, medicallead 100 may include segmented electrodes, each including electrodesegments extending along an arc less than 360 degrees (for example,90-120 degrees). Segmented electrodes may be useful for providing anelectrical stimulation field that is predominantly focused in aparticular transverse direction relative to the longitudinal axis ofmedical lead 100, and/or targeting a particular stimulation site.

Each of electrodes 104 and 105 can be made from an electricallyconductive, biocompatible material, such as platinum iridium. Inaddition, in some examples, at least one of electrodes 104 and 105 mayfunction as a sensing electrode that monitors internal, physiological,electrical signals of patient 12 (FIG. 1), such as electrical activityof brain 18 (FIG. 1) of patient 12. The configuration, type, and numberof electrodes 104 and 105 are merely exemplary. In other examples,medical lead 100 may include any configuration, type, and number ofelectrodes 104 and 105, and is not limited to the example illustrated inFIG. 4. As examples, stimulation and or sensing function may be providedby biopolar, multipolar or unipolar electrode combinations.

Within medical lead body 102, medical lead 100 also includes insulatedelectrical conductors 110 coupled to electrodes 104 and 105. Each ofconductors 110 is in electrical contact with its respective electrodeand extends to a proximal end of lead body 102 to facilitate anelectrical connection with an IMD (for example, IMD 20 of FIG. 1). Insome examples, conductors 110 are coiled along the length of medicallead body 102 (for example, in a multiconductor coil), but in otherexamples, conductors 110 may not be coiled. Because each of conductors110 is electrically coupled to a single one of electrodes 104 and 105,each of electrodes 104 and 105 may be independently activated or used.In other examples, a medical lead including multiple electrodes mayinclude a multiplexer or other switching device such that the medicallead may include fewer conductors than electrodes, while allowing eachof the electrodes to be independently activated. The switching devicemay be responsive to commands from the IMD or an external source toselectively couple the electrodes to the conductors for delivery ofstimulation or for sensing. Such a switching device may be particularlysuited for use with segmented electrodes.

Medical lead 100 includes three rotatable members 112, 113, 114positioned adjacent to the proximal end of medical lead body 102.Rotatable members 112, 113, 114 are individually rotatable by separatemotor assemblies 130A-130C respectively. For example, rotatable members112, 113, 114 may be placed under a burr cap covering a hole in theskull of a patient. When part of system 10 (FIG. 1), each of rotatablemembers 112, 113, 114 is mechanically coupled to and configured to bedriven by a rotating output shaft of motor 15 (FIG. 1). In addition,medical lead 100 includes anchor plate 111, which may be fixed to theskull of the patient. As referred to herein, rotation of rotatablemembers 112, 113, 114 is relative to the fixed position of anchor plate111.

Rotation of rotatable member 112 changes the radial orientation ofelectrodes 104, 105 relative to anchor plate 111. Thus, in examples inwhich electrodes 104, 105 include directional electrodes, theorientation of the simulation or sensing field may be adjusted viarotatable member 112.

Similarly, rotation of rotatable member 114 also moves a position ofelectrodes 104, 105 to adjust the spacing between the proximal end ofmedical lead body 102 and electrodes 104, 105. However, rotation ofrotatable member 114 directly varies spacing between electrodes 104, 105via opposing threads 115A and 115B. In particular, electrode 104 isconfigured to move linearly about lead body 102 during rotation ofrotatable member 114 based on interaction with thread 115A as electrode104 and thread 115A form a threaded joint. Likewise, electrode 105 isconfigured to move linearly about lead body 102 during rotation ofrotatable member 114 based on interaction with thread 115B as electrode105 and thread 115B form another threaded joint. During rotation ofrotatable member 114 electrode 105 will move in the opposite directionabout lead body 102 as compared to electrode 104 due to the oppositethreading of thread 115B as compared to thread 115A. In this manner,rotation of rotatable member 114 varies the pitch between electrodes104, 105.

Similarly, rotation of rotatable member 114 also moves a position ofelectrodes 104, 105 to adjust the spacing between the proximal end ofmedical lead body 102 and electrodes 104, 105. However, rotation ofrotatable member 114 directly varies spacing between electrodes 104, 105via opposing threads 115A and 115B. In particular, electrode 104 isconfigured to move linearly about lead body 102 during rotation ofrotatable member 114 based on interaction with thread 115A as electrode104 and thread 115A form a threaded joint. Likewise, electrode 105 isconfigured to move linearly about lead body 102 during rotation ofrotatable member 114 based on interaction with thread 115B as electrode105 and thread 115B form another threaded joint. During rotation ofrotatable member 114 electrode 105 will move in the opposite directionabout lead body 102 as compared to electrode 104 due to the oppositethreading of thread 115B as compared to thread 115A. In this manner,rotation of rotatable member 114 varies the pitch between electrodes104, 105.

As mentioned above, FIG. 4C illustrates motor assembly 130B ofmechanically adjustable medical lead 100. Motor assembly 130B may beconsidered representative of motor assemblies 130A and 130C. Motorassembly 130B includes stepper motor 131. Stepper motor 131 isconfigured to drive geartrain 132 within motor assembly 130B. Outputgear 134 is mounted on shaft 133, and is configured to drive rotatablemember 113 (not shown in FIG. 4C).

In some examples, motor assembly 130B may further include a sealedhousing, stepper motor 131 being within the sealed housing and includinga rotating output shaft. The rotating output shaft may be coupled to amechanical feedthrough, such as one of mechanical feedthroughs 400, 601,701 or 801. The output of the mechanical feedthrough may be coupled togeartrain 132 to drive rotatable member 113. As discussed with respectto FIG. 10A, the mechanical feedthrough may include a nutating shaftcoupled to the rotating output shaft of the motor and within the sealedhousing. Alternatively, the mechanical feedthrough may include a pair ofcoaxial shafts coupled with an offset pin and sealed with a flexibleseal including an oscillating cap, as with feedthroughs 601, 701 and801. Such a mechanical feedthrough may facilitate hermetic sealing ofstepper motor 131 and the corresponding motors of motor assemblies 130Aand 130C.

In further examples, a medical lead may only provide a single degree ofadjustability, for example, either a varying length or a varying pitchsuch that an engagement mechanism is not required. In any event, themotor may include a stepper motor. The use of a stepper motor combinedwith fine thread pitch of threaded joints within medical lead 100 mayprovide precise positioning. As one example, a stepper motor may have aresolution of 7840 steps per revolution. When combined with a 0.050 inchthread-pitch for a threaded joint within medical lead 100, such acombination would provide electrode position adjustment increments of0.050 inches divided by 7840, or 6.4×10⁻⁶ inches per step. While thisparticular example is in no way limiting to the scope of thisdisclosure, it does demonstrate that the precision adjustmentsfacilitated by medical lead 100 may be many orders of magnitude moreprecise than possible with only surgical positioning of electrodes.

In some examples, the precision of a motor may be verified or improvedby including one or more linear sensors to directly sense positioning ofone or more of lead body 102 and electrodes 104, 105. In some examples,such linear sensors may include linear variable differential transformer(LVDT) sensors.

FIG. 5 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient. For clarity, the techniques of FIG. 5 aredescribed with respect to system 10, including IMD 20 (FIG. 2) andmechanically adjustable medical lead 100 (FIG. 4).

First, processor 70 of IMD 20 receives an instruction to move theposition of one or both of electrodes 104, 105 of medical lead 100(140). For example, processor 70 of IMD 20 may receive the instructionfrom a control program stored in memory 72 of IMD 20 or processor 70 ofIMD 20 may receive the instruction from programmer 19. In some examples,a clinician may directly instruct processor 70 of IMD 20 to move theposition of one or both of electrodes 104, 105 via programmer 19.

Next, processor 70 of IMD 20 operates motor 15 to drive a rotatingoutput shaft of the motor and move a position of one or both ofelectrodes 104, 105 of medical lead 100 (142). For example, processor 70may operate motor 15 to drive rotatable member 112 to move a position ofelectrodes 104, 105 to adjust the spacing between the proximal end ofmedical lead body 102 and electrodes 104, 105 by varying an overalllength of medical lead 100. Alternatively or in addition, processor 70may operate motor 15 to drive rotatable member 114 to move a position ofelectrodes 104, 105 to directly vary spacing between electrodes 104, 105via opposing threads 115A and 115B. In this manner, IMD 20 and processor70 are suitable for implementing electrode positioning adjustmentsfacilitated by mechanically adjustable medical lead 100.

FIG. 6 is a cross-sectional view of mechanically adjustable medical lead200. Medical lead 200 includes force sensors 220, 221, which are eachconfigured to measure a resistance to movement of a position of anelectrode of the medical lead. Medical lead 200 may be utilized as a DBSlead and may, for example, correspond to mechanically adjustable medicallead 14 of FIG. 1. In other examples, medical lead 200 may be utilizedfor other sensing and or simulation of any tissue of a patient,including, but not limited to, spinal cord stimulation and sensing,peripheral nerve stimulation and sensing, pelvic nerve stimulation andsensing, gastric nerve stimulation and sensing, vagal nerve stimulationand sensing, stimulation and sensing of muscles or muscle groups,stimulation and sensing of an organ such as gastric system stimulationand sensing, stimulation and sensing concomitant to gene therapy andothers.

Proximal end 201 of medical lead 200 may be coupled to an IMD (forexample, IMD 20 of FIG. 1) via one or more conductive wires, such as ina lead extension (not shown). Medical lead 200 includes a medical leadbody 202 and electrodes 204 and 205. Medical lead body 202 may have asubstantially circular cross-sectional shape, but other shapes may alsobe used. Medical lead body 202 may be formed from an insulativebiocompatible material.

Electrode 205 is located at a distal portion of medical lead body 202,whereas electrode 204 is located more proximally along medical lead body202 as compared to electrode 205. As shown in FIG. 6, electrodes 204 and205 are ring electrodes extending substantially around the entireperiphery, for example, circumference, of medical lead 200. In otherexamples, instead of or in addition to electrodes 204 and 205, medicallead 200 may include segmented electrodes, each including electrodesegments extending along an arc less than 360 degrees (for example,90-120 degrees).

Each of electrodes 204 and 205 can be made from an electricallyconductive, biocompatible material, such as platinum iridium. Inaddition, in some examples, at least one of electrodes 204 and 205 mayfunction as a sensing electrode that monitors internal, physiological,electrical signals of patient 12 (FIG. 1), such as electrical activityof brain 18 (FIG. 1) of patient 12. The configuration, type, and numberof electrodes 204 and 205 are merely exemplary. In other examples,medical lead 200 may include any configuration, type, and number ofelectrodes 204 and 205, and is not limited to the example illustrated inFIG. 6.

Within medical lead body 202, medical lead 200 also includes insulatedelectrical conductors 210 coupled to electrodes 204 and 205. Conductors210 are in electrical contact with their respective electrode and extendto a proximal end of lead body 202 to facilitate an electricalconnection with an IMD (for example, IMD 20 of FIG. 1). In someexamples, conductors 210 are coiled along the length of medical leadbody 202 (for example, in a multiconductor coil), but in other examples,conductors 210 may not be coiled. Because each of conductors 210 iselectrically coupled to a single one of electrodes 204 and 205, each ofelectrodes 204 and 205 may be independently activated. In otherexamples, a medical lead including multiple electrodes may include amultiplexer or other switching device such that the medical lead mayinclude fewer conductors than electrodes, while allowing each of theelectrodes to be independently activated. The switching device may beresponsive to commands from the IMD or an external source to selectivelycouple the electrodes to the conductors for delivery of stimulation orfor sensing. Such a switching device may be particularly suited for usewith segmented electrodes.

Medical lead 200 includes two rotatable members 212, 214 positionedadjacent to the proximal end of medical lead body 202. For example,rotatable members 212, 214 may be placed under a burr cap covering ahole in the skull of a patient. When part of system 10 (FIG. 1), each ofrotatable members 212, 214 is mechanically coupled to and configured tobe driven by a rotating output shaft of motor 15 relative to anchorplate 211, which may be fixed to the skull of the patient. Rotation ofrotatable member 212 moves a position of electrodes 204, 205 to adjustthe spacing between the proximal end of medical lead body 202 andelectrodes 204, 205 by varying an overall length of medical lead. Inparticular, rotatable member 212 and lead body 202 combine to formthreaded joint 213. Threaded joint 213 transfers the rotation ofrotatable member 212 into substantially linear movement to move thepositions of electrodes 204, 205 and vary an overall length of medicallead 200.

Medical lead 200 further includes force sensor 220, which is configuredto measure a resistance to movement of the position of electrodes 204,205 by varying the overall length of medical lead 200. As force sensor220 is located between threaded joint 213 and electrodes 204, 205, forcesensor 220 may be configured to measure tensile strain on lead body 202.In one example, force sensor 220 includes a piezoelectric sensor mountedto an interior or exterior surface of lead body 202 or within lead body202. In the same or different examples, medical lead 200 may include acurrent sensor and force may be measured by monitoring current requiredto operate a motor used to drive rotatable member 212, for example,current through motor 15 (FIG. 1). Force sensor 220 is furtherconfigured to deliver a force signal based on the resistance to movementto a processor, such as processor 70 of IMD 20 (FIG. 2). The processormay control the motor used to drive rotatable member 212 based on theforce signal. In one example, the processor may control the motor usedto drive rotatable member 212 at least in part by limiting movement toprevent the resistance to movement as detected by force sensor 220 fromexceeding a predefined value.

Similarly, rotation of rotatable member 214 also moves a position ofelectrodes 204, 205 to adjust the spacing between the proximal end ofmedical lead body 202 and electrodes 204, 205. However, rotation ofrotatable member 214 directly varies spacing between electrodes 204, 205via opposing threads 215A and 215B. In particular, electrode 204 isconfigured to move linearly about lead body 202 during rotation ofrotatable member 214 based on interaction with thread 215A as electrode204 and thread 215A form a threaded joint. Likewise, electrode 205 isconfigured to move linearly about lead body 202 based during rotation ofrotatable member 214 based on interaction with thread 215B as electrode205 and thread 215B form another threaded joint. Due to the oppositethreading of thread 215B as compared to thread 215A, electrode 205 willmove in the opposite direction about lead body 202 as compared toelectrode 204 due to rotation of rotatable member 214. In this manner,rotation of rotatable member 214 varies the pitch between electrodes204, 205.

Medical lead 200 further includes force sensor 221, which is configuredto measure a resistance to movement of the position of electrodes 204,205 by varying the pitch between electrodes 204, 205. As force sensor221 is located between the motor and the threaded joints of threads215A, 215B and electrodes 204, 205, force sensor 221 may be configuredto measure rotational strain on rotatable member 214. In one example,force sensor 221 includes a piezoelectric sensor. In the same ordifferent examples, medical lead 200 may include a current sensor andforce may be measured by monitoring current required to operate a motorused to drive rotatable member 214, for example, current through motor15 (FIG. 1). Force sensor 221 is further configured to deliver a forcesignal based on the resistance to movement to a processor, such asprocessor 70 of IMD 20 (FIG. 2). The processor may control the motorused to drive rotatable member 214 based on the force signal. In oneexample, the processor may control the motor used to drive rotatablemember 214 at least in part by limiting movement to prevent theresistance to movement as detected by force sensor 221 from exceeding apredefined value.

In some examples, medical lead 200 may further include a motor, such asmotor 15 (FIG. 1) and optionally an engagement mechanism (not shown),such as a mechanical or magnetic clutch mechanism to selectively driveone or both of rotatable members 212, 214. In other examples, medicallead 200 may include a separate drive motor for each of rotatablemembers 212, 214. In further examples, a medical lead may only provide asingle degree of adjustability, for example, either a varying length ora varying pitch such that an engagement mechanism is not required. Inany event, the motor may include a stepper motor. The use of a steppermotor combined with fine thread pitch of threaded joints within medicallead 200 may provide precise positioning. In some examples, theprecision of a motor may be verified or improved by including one ormore linear sensors to directly sense positioning of one or more of leadbody 202 and electrodes 204, 205. In some examples, such linear sensorsmay include linear variable differential transformer (LVDT) sensors.

In the same or different examples, medical lead 200 may also furtherinclude a sealed housing, the motor being within the sealed housing andincluding a rotating output shaft. The rotating output shaft may becoupled to a mechanical feedthrough, such as one of mechanicalfeedthroughs 400, 601, 701 or 801. As discussed with respect to FIG.10A, the mechanical feedthrough may include a nutating shaft coupled tothe rotating output shaft of the motor and within the sealed housing.Alternatively, the mechanical feedthrough may include a pair of coaxialshafts coupled with an offset pin and sealed with a flexible sealincluding an oscillating cap, as with feedthroughs 601, 701 and 801.Such a mechanical feedthrough may facilitate hermetic sealing of themotor.

FIG. 7 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient based on a signal from a force sensor. Forclarity, the techniques of FIG. 7 are described with respect to system10, including IMD 20 (FIG. 2) and mechanically adjustable medical lead200 (FIG. 6).

First, processor 70 of IMD 20 receives an instruction to move theposition of one or both of electrodes 204, 205 of medical lead 200(240). For example, processor 70 of IMD 20 may receive the instructionfrom a control program stored in memory 72 of IMD 20 or processor 70 ofIMD 20 may receive the instruction from programmer 19. In some examples,a clinician may directly instruct processor 70 of IMD 20 to move theposition of one or both of electrodes 204, 205 via programmer 19. S

Next, processor 70 of IMD 20 operates motor 15 to drive a rotatingoutput shaft of the motor and move a position of one or both ofelectrodes 204, 205 of medical lead 200 (242). For example, processor 70may operate motor 15 to drive rotatable member 212 to move a position ofelectrodes 204, 205 to adjust the spacing between the proximal end ofmedical lead body 202 and electrodes 204, 205 by varying an overalllength of medical lead 200. Alternatively or in addition, processor 70may operate motor 15 to drive rotatable member 214 to move a position ofelectrodes 204, 205 to directly vary spacing between electrodes 204, 205via opposing threads 215A and 215B.

Prior to, during, and/or following the operation of motor 15 to drive arotating output shaft of the motor and move a position of one or both ofelectrodes 204, 205 of medical lead 200, processor 70 receiving a forcesignal from one or both of force sensors 220, 221 (244). The forcesignal represents a resistance to movement of the position of thecorresponding electrodes of medical lead 200. For example, the forcesignal from force sensor 220 represents a resistance to varying theoverall length of lead 200, whereas the force signal from force sensor220 represents a resistance to varying the spacing between electrodes204, 205.

Processor 70 then operates, based on the force signal, as well as theinstruction to move the position of one or both of electrodes 204, 205,motor 15 to drive one or both of rotatable members 212, 214 via arotating output shaft of motor 15, thereby moving a position of at leastone of electrodes 204, 205 to adjust a spacing between a proximal end ofmedical lead 200 and at least one of electrodes 204, 205 (246). In oneexample, processor 70 may operate motor 15 to limit the movement toprevent resistance to the movement from exceeding a predefined value. Inthis manner, IMD 20 and processor 70 are suitable for implementingelectrode positioning adjustments facilitated by mechanically adjustablemedical lead 200.

FIGS. 8A-8B illustrate cross-sectional views of mechanically adjustablemedical lead 300, which includes retractable electrode 330. Inparticular, FIG. 8A illustrates medical lead 300 with retractableelectrode 330 in a fully refracted position such that it issubstantially within the profile of lead body 302, whereas FIG. 8Billustrates medical lead 300 with retractable electrode 330 in anextended position beyond the profile of lead body 302. Medical lead 300may be utilized as a DBS lead and may, for example, correspond tomechanically adjustable medical lead 14 of FIG. 1. In other examples,medical lead 300 may be utilized for other sensing and or simulation ofany tissue of a patient, including, but not limited to, spinal cordstimulation and sensing, peripheral nerve stimulation and sensing,pelvic nerve stimulation and sensing, gastric nerve stimulation andsensing, vagal nerve stimulation and sensing, stimulation and sensing ofmuscles or muscle groups, stimulation and sensing of an organ such asgastric system stimulation and sensing, stimulation and sensingconcomitant to gene therapy and others.

Proximal end 301 of medical lead 300 may be coupled to an IMD (forexample, IMD 20 of FIG. 1) via one or more conductive wires, such as ina lead extension (not shown). Medical lead 300 includes a medical leadbody 302, electrodes 304 and 305 as well as retractable electrode 330.Medical lead body 302 may have a substantially circular cross-sectionalshape, but other shapes may also be used. Medical lead body 302 may beformed from an insulative biocompatible material.

Electrode 305 is located at a distal portion of medical lead body 302,whereas electrode 304 is located more proximally along medical lead body302 as compared to electrode 305. Electrodes 304 and 305 are ringelectrodes extending substantially around the entire periphery, forexample, circumference, of medical lead 300. In other examples, insteadof or in addition to electrodes 304 and 305, medical lead 300 mayinclude segmented electrodes, each including electrode segmentsextending along an arc less than 360 degrees (for example, 90-120degrees). In addition, retractable electrode 330 is located moreproximally along medical lead body 302 as compared to electrode 305,although with other designs one or more retractable electrode may belocated at any point along medical lead body 302.

Each of electrodes 304, 305 and 330 can be made from an electricallyconductive, biocompatible material, such as platinum iridium. Inaddition, in some examples, at least one of electrodes 304, 305 and 330may function as a sensing electrode that monitors internal,physiological, electrical signals of patient 12 (FIG. 1), such aselectrical activity of brain 18 (FIG. 1) of patient 12. Theconfiguration, type, and number of electrodes 304, 305 and 330 aremerely exemplary. In other examples, medical lead 300 may include anyconfiguration, type, and number of electrodes 304, 305 and 330, and isnot limited to the example illustrated in FIGS. 8A-8B.

Within medical lead body 302, medical lead 300 also includes insulatedelectrical conductors 310 coupled to electrodes 304 and 305. Conductors310 are in electrical contact with their respective electrode and extendto a proximal end of lead body 302 to facilitate an electricalconnection with an IMD (for example, IMD 20 of FIG. 1). In addition, theconductor of electrode 330 also extends to a proximal end of lead body302 to facilitate an electrical connection with an IMD. In otherexamples, electrode 330 may be electrically coupled to the conductor ofone of electrodes 304 or 305. In some examples, conductors 310 arecoiled along the length of medical lead body 302 (for example, in amulticonductor coil), but in other examples, conductors 310 may not becoiled. Because each of conductors 310 is electrically coupled to asingle one of electrodes 304 and 305, each of electrodes 304, 305 and330 may be independently activated. In other examples, a medical leadincluding multiple electrodes may include a multiplexer or otherswitching device such that the medical lead may include fewer conductorsthan electrodes, while allowing each of the electrodes to beindependently activated. The switching device may be responsive tocommands from the IMD or an external source to selectively couple theelectrodes to the conductors for delivery of stimulation or for sensing.Such a switching device may be particularly suited for use withsegmented electrodes.

Medical lead 300 includes two rotatable members 312, 314 positionedadjacent to the proximal end of medical lead body 302. For example,rotatable members 312, 314 may be placed under a burr cap covering ahole in the skull of a patient. When part of system 10 (FIG. 1), each ofrotatable members 312, 314 are mechanically coupled to and configured tobe driven by a rotating output shaft of motor 15. Rotation of rotatablemember 312 moves a position of retractable electrode 330 to selectivelydeploy and retract the retractable electrode 330 from medical lead body302. Rotatable member 312 forms threaded joint 313, which transfers therotation of rotatable member 312 into substantially linear movement toselectively deploy and retract the retractable electrode 330 frommedical lead body 302.

Similarly, rotation of rotatable member 314 also moves a position ofelectrode 304 to adjust the spacing between the proximal end of medicallead body 302 and electrode 304 via threaded joint 315 formed betweenrotatable member 314 and electrode 304. Rotation of rotatable member 314also varies spacing between electrodes 304, 305, as electrode 305 remainstationary during rotation of rotatable member 314. In particular,electrode 304 is configured to move linearly about lead body 302 duringrotation of rotatable member 314 based on interaction with thread 315.In this manner, rotation of rotatable member 314 varies the pitchbetween electrodes 304, 305.

In some examples, medical lead 300 may further include a rotatablemember and a threaded joint configured to vary an overall length ofmedical lead 300, as with rotatable member 112 and the threaded joint ofmedical lead 100 (FIG. 4).

In some examples, medical lead 300 may further include a motor, such asmotor 15 (FIG. 1) and optionally an engagement mechanism (not shown),such as a mechanical or magnetic clutch mechanism to selectively driveone or both of rotatable members 312, 314. In other examples, medicallead 300 may include a separate drive motor for each of rotatablemembers 312, 314. In further examples, a medical lead may only provide asingle degree of adjustability, for example, either a retractableelectrode or a varying pitch such that an engagement mechanism is notrequired. In any event, the motor may include a stepper motor. The useof a stepper motor combined with fine thread pitch of threaded jointswithin medical lead 300 may provide precise positioning. In someexamples, the precision of a motor may be verified or improved byincluding one or more linear sensors to directly sense positioning ofone or more of lead body 302 and electrodes 304, 305. In some examples,such linear sensors may include linear variable differential transformer(LVDT) sensors.

In the same or different examples, medical lead 300 may also furtherinclude a sealed housing, the motor being within the sealed housing andincluding a rotating output shaft. The rotating output shaft may becoupled to a mechanical feedthrough, such as one of mechanicalfeedthroughs 400, 601, 701 or 801. As discussed with respect to FIG.10A, the mechanical feedthrough may include a nutating shaft coupled tothe rotating output shaft of the motor and within the sealed housing.Alternatively, the mechanical feedthrough may include a pair of coaxialshafts coupled with an offset pin and sealed with a flexible sealincluding an oscillating cap, as with feedthroughs 601, 701 and 801.Such a mechanical feedthrough may facilitate hermetic sealing of themotor.

FIG. 9 is a flowchart illustrating an example technique for deploying aretractable electrode of a mechanically adjustable medical leadimplanted within a patient. For clarity, the techniques of FIG. 9 aredescribed with respect to system 10, including IMD 20 (FIG. 2) andmechanically adjustable medical lead 300 (FIGS. 8A-8B).

First, processor 70 of IMD 20 receives an instruction to deployretractable electrode 330 of medical lead 300 (340). For example,processor 70 of IMD 20 may receive the instruction from a controlprogram stored in memory 72 of IMD 20 or processor 70 of IMD 20 mayreceive the instruction from programmer 19. In some examples, aclinician may directly instruct processor 70 of IMD 20 to move theposition of one or both of electrodes 304, 330 via programmer 19.

Next, processor 70 of IMD 20 operates motor 15 to drive a rotatingoutput shaft of the motor to rotate rotatable member 312 and to deployretractable electrode 330 of medical lead 300 (342). Processor 70 of IMD20 may also operate motor 15 to drive a rotating output shaft of themotor to rotate rotatable member 312 in an opposing direction to retractretractable electrode 330 of medical lead 300. In addition, processor 70may operate motor 15 to drive rotatable member 314 to move a position ofelectrode 304 to directly vary spacing between electrodes 304, 305. Insome examples, processor 70 may receive force signals from force sensorsmonitoring resistance to movement of electrodes driven by one or both ofrotatable members 312, 314 and may operate motor 15 to drive thecorresponding rotatable members 312, 314 based on the force signals. Forexample, processor 70 may limit movement of retractable electrode 330 toprevent resistance to the movement of limiting movement of theretractable electrode to prevent resistance to the movement of theretractable electrode from exceeding a predefined value. In this manner,IMD 20 and processor 70 are suitable for implementing electrodepositioning adjustments facilitated by mechanically adjustable medicallead 300.

FIGS. 10A-10D illustrate components of a nutating mechanical feedthroughthat facilitates mechanical coupling to a rotating shaft within ahermetically sealed enclosure. FIG. 10A is a cross-sectional view of anutating mechanical feedthrough 400. Nutating mechanical feedthrough 400facilitates mechanical coupling to a rotating shaft within ahermetically sealed enclosure. For example, nutating mechanicalfeedthrough 400 may be suitable for connecting any of medical leads,100, 200 and 300 to motor 15.

Nutating mechanical feedthrough 400 includes an oscillating component,in this example, nutating shaft 402, which is supported by threeseparate bearings. A central portion of nutating shaft 402 is supportedby central bearing 410. Central bearing 410 allows nutating shaft 402 topivot relative to center plate 411. In some examples, central bearing410 may include a radial spherical bearing. Proximal end 403 of nutatingshaft 402 is supported by radial ball bearing 406 via plate 407.Similarly, distal end 404 of nutating shaft 402 is supported by radialball bearing 408 via plate 409. Whereas plates 407, 409 rotate, nutatingshaft 402 does not substantially rotate but only nutates. However, eventhough nutating shaft 402 does not rotate, nutating shaft 402rotationally couples plates 407, 409 to one another. In this manner, therotational motion of one of plates 407, 409 is transferred to the otherof plates 407, 409 via nutating shaft 402.

Because nutating shaft 402 does not rotate, nutating shaft 402facilitates hermetic sealing to isolate plates 407, 409 from oneanother. In the example of nutating mechanical feedthrough 400, thehermetic boundary between rotating plates 407, 409 includes housing 420,center plate 411 and flexible seals 430A, 430B. Flexible seals 430A,430B provide a double hermetic barrier for nutating mechanicalfeedthrough 400. By design, the flexible seals 430A, 430B flex and maybe subject to failure from cycling fatigue, such that the redundancyoffered by additional barriers may improve the reliability of thehermetic sealing as compared to a design with a single flexible seal. Inother examples, only a one of flexible seals 430A, 430B may be used toprovide a single hermetic barrier within a nutating mechanicalfeedthrough. A proximal side of flexible seal 430A covers a distal sideof central bearing 410, and a distal side of flexible seal 430A issecured to a distal portion of the nutating shaft 402 located distallyrelative to central bearing 410. Conversely, a distal side of flexibleseal 430B covers a proximal side of central bearing 410, and a proximalside of flexible seal 430B is secured to a proximal portion of thenutating shaft 402 located proximally relative to central bearing 410.

In some examples, flexible seals 430A, 430B each include a metalbellows, such as an electroformed metal bellows. The metal bellows mayinclude alternating layers of copper and nickel. In some examples,electroforming such a metal bellows may include plating the alternatinglayers of copper and nickel on an aluminum mandrel before dissolving thealuminum mandrel with an acid to leave the metal bellows behind. Thedesign of nutating mechanical feedthrough 400 and the metal bellows inparticular may be selected to limit the operating stress on the metalbellows during the nutating motion of nutating shaft 402. In oneexample, the metal bellows may be subjected to an operating stress ofless than forty percent of its yield stress. In another example, themetal bellows may be subjected to an operating stress of no more thantwenty percent of its yield stress. Limiting the operating stress of themetal bellows to the smallest possible percentage of its yield stressfacilitates forming a reliable hermetic boundary with the metal bellows.Limiting the operating stress may increase the service life of the metalbellows.

Nutating mechanical feedthrough 400 further includes weld joint 434,which seals an interface of flexible seal 430A and housing 420 andincludes weld joint 436, which seals an interface of flexible seal 430Aand nutating shaft 402. In this manner, housing 420, center plate 411,flexible seal 430A, and weld joints 434, 436 combine to form a hermeticboundary between plates 407, 409 to contain hermetically sealedenclosure 421. Weld joints 434, 436 may be considered representative ofweld joints for flexible seals 340A, 430B, and additional weld jointsfor flexible seal 430B are not illustrated. The interface between centerplate 411 and housing 420 may also include weld joints to insurehermetic sealing. Note that plate 407 should be considered to beentirely within hermetically sealed enclosure 421 and the remainingboundaries of hermetically sealed enclosure 421 are not illustrated inFIG. 10A. As an example, a motor driving plate 407 may have a sealedhousing, and the sealed motor housing may be sealed to housing 420 toform the entire boundary of hermetically sealed enclosure 421, forexample, as illustrated in the example of FIG. 11.

In some examples, hermetically sealed enclosure 421 may be filled with aselected fluid, such as an inert gas, oil or other liquid. Hermeticallysealed enclosure 421 may further provide one or more of the additionaldesign options for an implantable medical device. Hermetically sealedenclosure 421 may enable the option of removing traditional electricalfeedthroughs from neurostimulation system designs employing rotary primemovers. Hermetically sealed enclosure 421 may further facilitate placingboth ends of an electrical feedthrough in a dry operating environment.Hermetically sealed enclosure 421 may further allow critical mechanicalcomponents of an implantable medical device, not just motors and otherelectrical components, to be sealed within. In addition, hermeticallysealed enclosure 421 may remediate corrosion and dendritic growth issuesby depriving these processes of the chemical fuel required to sustainthem.

FIG. 10B illustrates a close-up view of central bearing 410, whichsupports a central portion of nutating shaft 402. Central bearing 410allows nutating shaft 402 to pivot relative to center plate 411. Asfurther indicated in FIG. 10B, central bearing 410 is further supportedby set screw 414, which includes bearing surface 415 to receive centralbearing 410. In this manner, set screw 414 represents a ball retentionfeature. As illustrated in FIGS. 10C and 10D, set screw 414 includesthreads 416 to couple to corresponding threads in center plate 411 andslot 418 to receive a driver head, such as a flathead screwdriver duringassembly of nutating mechanical feedthrough 400.

The inclusion of a ball retention feature may provide one or more designoptions. A ball retention feature could be used wherever a ball featureis used, such as central bearing 410, which means that it could be usedon center plate 411 and/or on plates 407, 409. In addition, the use of aball retention feature would allow tolerances of feature size, position,material properties and other characteristics to be liberalized. Due tothe nature of the ongoing contact between set screw 414 and centralbearing 410 during operation of mechanical feedthrough 400, theproperties of central bearing 410 may be controlled by selectingmatching of ball and retainer radii, selecting materials for ball andretainer, including the use of coatings, such as diamond-like carbon onthe ball and/or on the retainer to improve wear characteristics.

While central bearing 410 is in direct contact with bearing surface 415of set screw 414, in an alternate design, set screw 414 may be replacedwith a set screw, spring and separate component including a bearingsurface in a stacked arrangement. Such an arrangement may facilitate andadjustable level of force on between the bearing surface and centralbearing 410 by varying the depth of the set screw. Such a designprovides increased manufacturing tolerances as compared to the assemblyshown in FIG. 10B.

FIG. 11 is a conceptual diagram of assembly 500, which includes motor 15(FIG. 1) within a hermetically sealed enclosure 421 and nutatingmechanical feedthrough 400, which facilitates mechanical couplingrotating output shaft 516 of motor 15 through the boundary ofhermetically sealed enclosure 421. In particular, rotating output shaft516 drives plate 407 of nutating mechanical feedthrough 400 to nutatenutating shaft 402. In turn, nutating shaft 402 functions to rotateplate 409, which drives load 502.

In different examples, load 502 may represent a mechanically adjustablemedical lead, such as any of mechanically adjustable medical leads 100,200 and 300 or other mechanical device. For example, plate 409 mayrepresent one of the rotating members 112, 113, 114, 212, 214, 312, 314of medical leads 100, 200 and 300 or plate 409 may be mechanicallycoupled to one of the rotating members 112, 113, 114, 212, 214, 312, 314of medical leads 100, 200 and 300 directly or via an engagementmechanism, such as a mechanical or magnetic clutch engagement mechanism.

Assembly 500 forms a substantially sealed enclosure 421 encasing motor15, rotating output shaft 516, the proximal end of the nutating shaftand central bearing 410. As discussed with respect to FIG. 10A,substantially sealed enclosure 421 may be a hermetically sealedenclosure.

FIG. 12 is a flowchart illustrating an example technique for operating amotor within a hermetically sealed enclosure to adjust a spacing betweena proximal end of a medical lead and an electrode of the medical lead.For clarity, the techniques of FIG. 12 are described with respect tosystem 10, including IMD 20 (FIG. 2), mechanically adjustable medicallead 100 (FIG. 4) and assembly 500 (FIG. 11). The techniques of FIG. 12may also be practiced using the mechanical feedthroughs of FIGS. 15-17The techniques of FIG. 12 may also be practiced using one of themechanical feedthroughs of FIGS. 15-17 in combination with amechanically adjustable lead, such as lead 100.

First, processor 70 of IMD 20 receives an instruction to move theposition of one or both of electrodes 104, 105 of medical lead 100(540). For example, processor 70 of IMD 20 may receive the instructionfrom a control program stored in memory 72 of IMD 20 or processor 70 ofIMD 20 may receive the instruction from programmer 19. In some examples,a clinician may directly instruct processor 70 of IMD 20 to move theposition of one or both of electrodes 104, 105 via programmer 19.

Next, processor 70 of IMD 20 operates motor 15, which is located withinsealed enclosure 421, which may be a hermetically sealed enclosure, todrive a rotating output shaft of the motor and move a position of one orboth of electrodes 104, 105 of medical lead 100 (542). For example,processor 70 may operate motor 15 to drive rotatable member 112 to movea position of electrodes 104, 105 to adjust the spacing between theproximal end of medical lead body 102 and electrodes 104, 105 by varyingan overall length of medical lead 100. Alternatively or in addition,processor 70 may operate motor 15 to drive rotatable member 114 to movea position of electrodes 104, 105 to directly vary spacing betweenelectrodes 104, 105 via opposing threads 115A and 115B. While thetechniques of FIG. 12 are described with respect to mechanicallyadjustable medical lead 100, the described techniques are alsoapplicable to other mechanically adjustable medical leads, such asmechanically adjustable medical leads 200 and 300.

FIG. 13 is a flowchart illustrating an example technique formanufacturing a nutating mechanical feedthrough that facilitatesmechanical coupling to a rotating shaft within a hermetically sealedenclosure. For clarity, the techniques of FIG. 13 are described withrespect to system 10, including IMD 20 (FIG. 2), mechanically adjustablemedical lead 100 (FIG. 4) and assembly 500 (FIG. 11).

The techniques include mechanically coupling rotating output shaft 516of motor 15 within a sealed housing to proximal end 403 of nutatingshaft 402 (550). As mentioned above, nutating shaft 402 is supported bycentral bearing 410. Nutating shaft 402 passes through boundary of thesealed environment, whereas central bearing 410 is within the sealedhousing. The techniques further include forming a first hermetic seal atan interface between housing 420, which contains the sealed environmentand flexible seal 430A, a proximal side of flexible seal 430A covering adistal side of central bearing 410 (552). Weld joint 434 represents oneexample of such a first hermetic seal. The techniques further includeforming a second hermetic seal at an interface between a distal portionof nutating shaft 402 and a distal side of flexible seal 430A (554).Weld joint 436 represents one example of such a first hermetic seal. Asmentioned above, housing 420, flexible seal 430A, weld joint 434 andweld joint 436 may combine to form a hermetically sealed enclosureencasing motor 15, rotating output shaft 516, proximal end 403 ofnutating shaft 402 and central bearing 410.

The techniques may further include mechanically coupling distal end 404of nutating shaft 402 to load 502 (556). In one example, load 502represents a rotatable member of a mechanically adjustable medical lead,such that nutation of nutating shaft 402 is configured to rotate therotatable member of the mechanically adjustable medical lead to move aposition of an electrode of the mechanically adjustable medical lead toadjust a spacing between a proximal end of the medical lead and theelectrode.

FIG. 14 is a flowchart illustrating an example technique for adjustingthe position of an electrode of a mechanically adjustable medical leadimplanted within a patient based on a physiological condition of thepatient. For clarity, the techniques of FIG. 14 are described withrespect to system 10, including IMD 20 (FIG. 2) and mechanicallyadjustable medical lead 100 (FIG. 4). The techniques of FIG. 14 may alsobe practiced using one of the mechanical feedthroughs of FIGS. 15-17 incombination with a mechanically adjustable lead, such as lead 100.

First, processor 70 of IMD 20 receives an instruction includingparameters for locating the position of one or both of electrodes 104,105 of medical lead 100 based on physiological condition of patient 12(560). For example, processor 70 of IMD 20 may receive the instructionfrom a control program stored in memory 72 of IMD 20 or processor 70 ofIMD 20 may receive the instruction from programmer 19. In some examples,a clinician may directly instruct processor 70 of IMD 20 to move theposition of one or both of electrodes 104, 105 via programmer 19 basedon the parameters for locating the position of one or both of electrodes104, 105 of medical lead 100 based on physiological condition of patient12.

Processor 70 monitors one or more physiological conditions of patient 12(562). The physiological conditions of patient 12 may indicate anefficacy of a therapy or sensing thereby providing an indication of thesuitability of the positioning of electrodes 104, 105. In some examples,physiological conditions of patient 12 may be at least partiallymonitored via electrodes 104, 105. For example, the physiologicalconditions may include patient activity level, patient posture, patienttremors, patient sleep characteristics and/or patient brain signalsmonitored over time. In different examples, the monitored physiologicalconditions may be monitored over various time periods such as timeperiods of a week to time periods of less than one second. In someparticular examples, the parameters for locating the position of one orboth of electrodes 104, 105 may include particular brain signalcharacteristics or biomarkers.

In some examples, the biomarker includes a particular signalcharacteristic, such as, but not limited to, any one or more of a timedomain characteristic of a bioelectrical brain signal (e.g., a mean,median, peak or lowest amplitude, instantaneous amplitude, waveformmorphology, pulse frequency or pulse to pulse variability), a frequencydomain characteristic of a bioelectrical brain signal (e.g., an energylevel in one or more frequency bands), a pattern of the bioelectricalbrain signal over time, or some other measurable characteristic of asensed bioelectrical brain signal. In some cases, the biomarker may beconsidered the absence of a particular characteristic (e.g., the energylevel in a particular frequency band is not over a threshold level). Thepresence or absence of a signal characteristic may be indicative of aparticular patient state and or electrode positioning. When a sensedbioelectrical brain signal includes, or in some cases, does not include,the signal characteristic, the sensed bioelectrical brain signal mayindicate patient 12 is in a state in which the effects of therapy mayhave changed, e.g., diminished relative to a baseline state in which theefficacious therapy was observed. The biomarker may be specific topatient 12, a patient condition, or both, such that the biomarkers basedon which the notifications are generated may differ between patients.Thus, the sensed bioelectrical brain signal may indicate an efficacy ofthe therapy.

In some examples, in order to determine whether a sensed bioelectricalbrain signal includes the biomarker, processor 70 may compare a timedomain characteristic (e.g., an amplitude) of the sensed bioelectricalbrain signal with a stored value, compare a particular power levelwithin a particular frequency band of the bioelectrical brain signal toa stored value, determine whether the sensed bioelectrical brain signalsubstantially correlates to a template, or combinations thereof. Forexample, processor 70 may determine one or more frequency bandcharacteristics of a sensed bioelectrical brain signal and determine thesensed bioelectrical brain signal includes the biomarker in response todetermining the one or more frequency band characteristics meet aparticular set of criteria associated with generating the notification.As an example, in response to determining a sensed bioelectrical brainsignal has a beta band power level that is greater than the beta bandpower level of a baseline bioelectrical brain signal, and a gamma bandpower level that is less than the gamma band power level of the baselinebioelectrical brain signal, processor 70 may determine the sensedbioelectrical brain signal includes a biomarker that indicates a changein efficacy of therapy delivered by IMD 20 (relative to the baselinestate). In this case, the biomarker includes the above-identified powerlevel conditions in the beta and gamma bands. As another example,processor 70 may determine the sensed bioelectrical brain signalincludes the biomarker in response to determining the sensedbioelectrical brain signal does not substantially correlate (e.g.,correlate or nearly correlate) with a template signal. Other techniquesare also contemplated.

The biomarker may be determined based on a bioelectrical brain signalsensed when therapy delivery by IMD 20 was determined to be efficacious,e.g., based on a subjective patient 12 rating or other patient input,based on a sensed parameter (e.g., a physiological signal or based on apatient activity level determined based on signals generated by one ormore motion sensors), or any other technique or combinations oftechniques. In some examples, processor 70 may determine the biomarkerby at least determining a first signal characteristic of a bioelectricalbrain signal sensed when therapy delivery by IMD 20 was determined to beefficacious. The first signal characteristic may be indicative of apatient state in which IMD 20 is delivering efficacious therapy topatient 12 and the biomarker may be selected to be indicative of apatient state in which therapy delivery by IMD 20 is not sufficientlyefficacious. In this example, the biomarker may be a signalcharacteristic of a sensed bioelectrical brain signal that is not equalto the first signal characteristic and is outside of a tolerance rangedefined relative to the first signal characteristic. For example, if thefirst signal characteristic is a first power level within a beta band ofa sensed bioelectrical brain signal, a biomarker may be a power levelwithin the beta band that is not equal to the first power level or anyvalue within a tolerance range of the first power level.

In another example, processor 70 may determine the biomarker by at leastdetermining a second signal characteristic of a bioelectrical brainsignal sensed when patient 12 is in a state in which efficacious effectsof therapy delivery by IMD 20 are not observed (e.g., a state prior toany therapy delivery by IMD 20 or a state in which IMD 20 is otherwisenot delivering therapy to patient 12). Again, the biomarker may beselected to be indicative of a patient state in which therapy deliveryby IMD 20 is not sufficiently efficacious. Thus, in this example, thebiomarker may be the second signal characteristic and values within atolerance range of the second signal characteristic (e.g., the tolerancerange measured relative to the second signal characteristic defines arange of values for the biomarker). For example, if the second signalcharacteristic is a second power level within a beta band of a sensedbioelectrical brain signal, a biomarker may be a power level within thebeta band that is equal to the second power level or any value within atolerance range of the second power level.

In some examples, the stimulation therapy delivered via electrodes 104,105 may be varied in combination with the positioning of electrodes 104,105. Adjusting the therapy may include, for example, changing parametersassociated with a therapy such as stimulation amplitude includingcurrent and/or voltage amplitude, pulse width, pulse rate, the number ofactivated leads or electrodes in a group or program, electrodecombination, electrode polarity and/or other therapy parameteradjustments.

Prior to, during, and/or following the monitoring of the physiologicalconditions of patient 12, processor 70 of IMD 20 operates motor 15 todrive a rotating output shaft of the motor and move a position of one orboth of electrodes 104, 105 of medical lead 100 (564). For example,processor 70 may operate motor 15 to drive rotatable member 112 to movea position of electrodes 104, 105 to adjust the spacing between theproximal end of medical lead body 102 and electrodes 104, 105 by varyingan overall length of medical lead 100. Alternatively or in addition,processor 70 may operate motor 15 to drive rotatable member 114 to movea position of electrodes 104, 105 to directly vary spacing betweenelectrodes 104, 105 via opposing threads 115A and 115B. In this manner,IMD 20 and processor 70 are suitable for implementing electrodepositioning adjustments facilitated by mechanically adjustable medicallead 100.

FIG. 15 illustrates a cross-sectional view of assembly 600, whichincludes motor 602 and mechanical feedthrough 601. Mechanicalfeedthrough 601 facilitates mechanical coupling to rotating shaft 640from within hermetically sealed enclosure 621.

Mechanical feedthrough 601 includes a pair of coaxial shafts 610, 640coupled with offset pin 618 and sealed with flexible seal 630. Flexibleseal 630 includes oscillating cap 632, which is fixed relative to offsetpin 618 such that oscillating cap 632 and offset pin 618 represent afunctionally unitary component.

Motor 602 operates to drives coaxial shaft 640, which is locate outsidehermetically sealed enclosure 621 via mechanical feedthrough 601.Mechanical feedthrough 601 includes motor output shaft 604, which ismechanically coupled to gear 606 and supported by bearings 605, whichare attached to housing 603. Gear 606 drives gear 608, which is coupledto coaxial shaft 610. Coaxial shaft 610 is supported by bearings 611,which are attached to housing 603. Offset bearing support 612 is coupledto, and driven in a circular motion by, coaxial shaft 610 about therotational axis of coaxial shaft 610. Offset bearing support 612 drivesoffset pin 618, which is fixed relative to oscillating cap 632. Bearings613 support the interface between offset pin 618 and offset bearingsupport 612.

Oscillating cap 632 is prevented from substantially rotating by isconnection to bellows 631, which is secured to housing 603. Nonetheless,the circular motion of offset bearing support 612 drives offset pin 618and oscillating cap 632 in an equivalent oscillating motion withoutrotation. Offset pin 618 extends past oscillating cap 632 and outsidethe hermetic boundary to drive offset bearing support 642 in a circularmotion. Bearings 643 support the interface between offset bearingsupport 642 and offset pin 618. Offset bearing support 642 is fixedrelative to coaxial shaft 640, such that the circular motion of offsetbearing support 642 drives rotation of coaxial shaft 640. Coaxial shaft640 is supported by bearings 641 in housing 603 and the distal end 646of coaxial shaft 640 extends beyond the perimeter of housing 603 todrive a component outside the hermetically sealed enclosure 621.

Because cap 632 does not rotate, cap 632, facilitates hermetic sealingbetween coaxial shafts 610, 640 while allowing the mechanical couplingof coaxial shafts 610, 640. In the example of mechanical feedthrough601, the hermetic boundary between coaxial shafts 610, 640 includeshousing 603, bellows 631, oscillating cap 632 and weld joints 634, 636.

In the example of assembly 600, motor 602, first coaxial shaft 610, andportions of offset pin 618 and oscillating cap 632 are within thehermetically sealed enclosure 621. As illustrated by this example,mechanical feedthrough 601 facilitates mechanical coupling rotatingshaft 640 from within hermetically sealed enclosure 621. For example,mechanical feedthrough 601 may be suitable for connecting any of medicalleads, 100, 200 and 300 to a motor, such as motor 602 or motor 15.

The hermetically sealed enclosure is formed by housing 603 and flexibleseal 630, which includes bellows 631 and oscillating cap 632. Mechanicalfeedthrough 601 further includes weld joint 634, which seals aninterface of bellows 631 and housing 603 and weld joint 636, which sealsan interface of bellows 631 and oscillating cap 632. In this manner,housing 603, bellows 631, oscillating cap 632, and weld joints 634, 636combine to form a hermetic boundary between coaxial shafts 610, 640 tocontain hermetically sealed enclosure 621.

In some examples, bellows 631 may include a metal bellows, such as anelectroformed metal bellows. The metal bellows may include alternatinglayers of copper and nickel. In some examples, electroforming such ametal bellows may include plating the alternating layers of copper andnickel on an aluminum mandrel before dissolving the aluminum mandrelwith an acid to leave the metal bellows behind. The design of mechanicalfeedthrough 601 and the metal bellows in particular may be selected tolimit the operating stress on the metal bellows during the motion ofoscillating cap 632. In one example, the metal bellows may be subjectedto an operating stress of less than forty percent of its yield stress.In another example, the metal bellows may be subjected to an operatingstress of no more than twenty percent of its yield stress. Limiting theoperating stress of the metal bellows to the smallest possiblepercentage of its yield stress facilitates forming a reliable hermeticboundary with the metal bellows. Limiting the operating stress mayincrease the service life of the metal bellows.

In some examples, hermetically sealed enclosure 621 may be filled with aselected fluid, such as an inert gas, oil or other liquid. Hermeticallysealed enclosure 621 may further provide one or more of the additionaldesign options for an implantable medical device. Hermetically sealedenclosure 621 may enable the option of removing traditional electricalfeedthroughs from neurostimulation system designs employing rotary primemovers. Hermetically sealed enclosure 621 may further facilitate placingboth ends of an electrical feedthrough in a dry operating environment.Hermetically sealed enclosure 621 may further allow critical mechanicalcomponents of an implantable medical device, not just motors and otherelectrical components, to be sealed within. In addition, hermeticallysealed enclosure 621 may remediate corrosion and dendritic growth issuesby depriving these processes of the chemical fuel required to sustainthem.

In the example illustrated in FIG. 15, housing 603 is formed from twohousing components 603A, 603B for purposes of manufacturability. Housingcomponents 603A, 603B are joined with weld joins 650 to maintain thehermetic boundary. The configuration of housing 603 including housingcomponents 603A, 603B is merely exemplary and any number ofconfigurations are possible. In addition, the mechanical couplingbetween motor shaft 604 and the output provided by coaxial shaft 640 isalso merely exemplary, and alternative configurations are possible,including any variety of gear combinations and designs are possiblewithin the spirit of this disclosure. In addition, multiple variationsof mechanical feedthrough 601 are also within the spirt of thisdisclosure. Two such variations are described with respect to FIGS. 16and 17.

FIG. 16 illustrates a cross-sectional view of assembly 700, whichincludes motor 702 and mechanical feedthrough 701. Mechanicalfeedthrough 701 facilitates mechanical coupling to rotating shaft 740from within hermetically sealed enclosure 721. Mechanical feedthrough701 includes a pair of coaxial shafts 710, 740 coupled with offset pin718 and sealed with flexible seal 730. Flexible seal 730 includesoscillating cap 732. Offset pin 718 is fixed relative to coaxial shaft740 such that offset pin 718 and coaxial shaft 740 represent afunctionally unitary component. With the example of assembly 700, offsetpin 718 and coaxial shaft 740 are outside the hermetically sealedenclosure 721.

Assembly 700 is functionally similar to assembly 600. In addition, likenumbered elements of assembly 700 correspond to the like numberedelements of assembly 600. For example, motor 702 corresponds to motor602, housing 703 corresponds to housing 603, flexible seal 730corresponds to flexible seal 630, etc. For brevity, elements of assembly700 that are the same or similar to the corresponding elements ofassembly 600 are described in limited or no detail with respect toassembly 700.

Motor 702 operates to drives coaxial shaft 740, which is locate outsidehermetically sealed enclosure 721 via mechanical feedthrough 701.Mechanical feedthrough 701 includes motor output shaft 704, which ismechanically coupled to gear 706 and supported by bearings 705, whichare attached to housing 703. Gear 706 drives gear 708, which is coupledto coaxial shaft 710. Coaxial shaft 710 is supported by bearings 711,which are attached to housing 703. Offset bearing support 712 is coupledto, and driven in a circular motion by, coaxial shaft 710 about therotational axis of coaxial shaft 710. Offset bearing support 712 drivesoscillating cap 732. Bearings 713 support the interface betweenoscillating cap 732 and offset bearing support 712.

Oscillating cap 732 is prevented from substantially rotating by isconnection to bellows 731, which is secured to housing 703. Nonetheless,the circular motion of offset bearing support 712 drives oscillating cap732 in an equivalent oscillating motion without rotation. Oscillatingcap 732 drives offset pin 718, which is located outside the hermeticboundary, in a circular motion. Bearings 719 support the interfacebetween oscillating cap 732 and offset pin 718. Offset pin 718 andoffset platform 739 are fixed relative to coaxial shaft 740, such thatthe circular motion of offset platform 739 drives rotation of coaxialshaft 740. Coaxial shaft 740 is supported by bearings 741 in housing 703and the distal end 746 of coaxial shaft 740 extends beyond the perimeterof housing 703 to drive a component outside the hermetically sealedenclosure 721.

FIG. 17 illustrates a cross-sectional view of assembly 800, whichincludes motor 802 and mechanical feedthrough 801. Mechanicalfeedthrough 801 facilitates mechanical coupling to rotating shaft 840from within hermetically sealed enclosure 821. Mechanical feedthrough801 includes a pair of coaxial shafts 810, 840 coupled with offset pin818 and sealed with flexible seal 830. Flexible seal 830 includesoscillating cap 832. Offset pin 818 is fixed relative to coaxial shaft810 such that offset pin 818 and coaxial shaft 810 represent afunctionally unitary component. With the example of assembly 800, offsetpin 818 and coaxial shaft 810 are within the hermetically sealedenclosure 821.

Assembly 800 is functionally similar to assembly 600. In addition, likenumbered elements of assembly 800 correspond to the like numberedelements of assembly 600. For example, motor 802 corresponds to motor602, housing 803 corresponds to housing 603, flexible seal 830corresponds to flexible seal 630, etc. For brevity, elements of assembly800 that are the same or similar to the corresponding elements ofassembly 600 are described in limited or no detail with respect toassembly 800.

Motor 802 operates to drives coaxial shaft 840, which is locate outsidehermetically sealed enclosure 821 via mechanical feedthrough 801.Mechanical feedthrough 80lincludes motor output shaft 804, which ismechanically coupled to gear 806 and supported by bearings 805, whichare attached to housing 803. Gear 806 drives gear 808, which is coupledto coaxial shaft 810. Coaxial shaft 810 is supported by bearings 811,which are attached to housing 803. Offset platform 809 is coupled to,and driven in a circular motion by, coaxial shaft 810 about therotational axis of coaxial shaft 810. Offset pin 818 and offset platform809 are fixed relative to coaxial shaft 810, such that rotation ofcoaxial shaft 810 drives circular motion of offset platform 809 andoffset pin 818.

Offset pin 818 drives oscillating cap 832. Bearings 819 support theinterface between offset pin 818 and oscillating cap 832. Oscillatingcap 832 is prevented from substantially rotating by is connection tobellows 831, which is secured to housing 803. Nonetheless, the circularmotion of offset pin 818 drives oscillating cap 832 in an equivalentoscillating motion without rotation. Oscillating cap 832 drives offsetbearing support 842, which is located outside the hermetic boundary, ina circular motion. Bearings 843 support the interface betweenoscillating cap 832 and offset bearing support 842. Offset bearingsupport 842 is fixed relative to coaxial shaft 840, such that thecircular motion of offset bearing support 842 drives rotation of coaxialshaft 840. Coaxial shaft 840 is supported by bearings 841 in housing 803and the distal end 846 of coaxial shaft 840 extends beyond the perimeterof housing 803 to drive a component outside the hermetically sealedenclosure 821.

FIG. 18 is a flowchart illustrating an example technique formanufacturing a mechanical feedthrough that facilitates mechanicalcoupling to a rotating shaft within a hermetically sealed enclosure. Forclarity, the techniques of FIG. 18 are described with respect to system10, including IMD 20 (FIG. 2), mechanically adjustable medical lead 100(FIG. 4) and assembly 600 (FIG. 15).

The techniques include forming a first hermetic seal at an interfacebetween bellows 631 and oscillating cap 632 (852). Weld joint 636represents one example of such a first hermetic seal. The techniquesfurther include forming a second hermetic seal at an interface betweenhousing 603, which contains the sealed environment and flexible seal 630(854). Weld joint 434 represents one example of such a first hermeticseal. The techniques optionally include assembling and sealing housingcomponents 603A, 603B. Weld joint 650 represents one example of such ahermetic seal sealing housing components 603A, 603B. For example,assembling and sealing housing components 603A, 603B may occur betweensteps 852 and 854. As mentioned above, housing 603, flexible seal 430,weld joints 634, 636, 650 may combine to form a hermetically sealedenclosure 621 encasing motor 602, gears 606, 608 first coaxial shaft610, and portions of offset pin 618 and oscillating cap 632.

The techniques may further include mechanically coupling distal end 646of coaxial shaft 640 to a load (556). In one example, the load mayrepresents a rotatable member of a mechanically adjustable medical lead,such that rotation of coaxial shaft 640 is configured to rotate therotatable member of the mechanically adjustable medical lead to move aposition of an electrode of the mechanically adjustable medical lead toadjust a spacing between a proximal end of the medical lead and theelectrode.

While the description primarily refers to implantable electrical medicalleads and implantable medical devices that deliver electricalstimulation therapy to a patient's brain, for example, DBS, the featuresand techniques described herein are useful in other types of medicaldevice systems, which may include other types of implantable medicalleads and implantable medical devices. For example, the features andtechniques described herein may be used in systems with medical devicesthat deliver electrical stimulation therapy to a patient's heart, forexample, pacemakers, and pacemaker-cardioverter-defibrillators. As otherexamples, the features and techniques described herein may be embodiedin systems that deliver other types of electrical stimulation therapy(for example, spinal cord stimulation, peripheral nerve stimulation,pelvic nerve stimulation, gastric nerve stimulation or vagal nervestimulation), stimulation of at least one muscle or muscle groups,stimulation of at least one organ such as gastric system stimulation,stimulation concomitant to gene therapy, and, in general, stimulation ofany tissue of a patient.

In addition, while the examples shown in the figures include medicalleads coupled at their proximal ends to a stimulation therapy generatorin, for example, an implantable medical device, located remotely fromthe electrodes, other configurations are also possible and contemplated.In some examples, a medical lead comprises a portion of a housing, or amember coupled to a housing, of a stimulation generator locatedproximate to or at the stimulation site, for example, as amicrostimulator. In other examples, a medical lead comprises a member atstimulation site that is wirelessly coupled to an implanted or externalstimulation generator or generator.

Some examples of this disclosure are described below.

Example 1A

An assembly comprising: a sealed housing; a motor within the sealedhousing, the motor including a rotating output shaft; a nutating shaft,wherein a proximal end of the nutating shaft is coupled to the rotatingoutput shaft and within the sealed housing; a central bearing passingthrough the sealed housing and supporting a central portion of thenutating shaft and within the sealed housing; and a flexible seal, aproximal side of the flexible seal covering a distal side of the centralbearing, and a distal side of the flexible seal being secured to adistal portion of the nutating shaft located distally relative to thecentral bearing, wherein the sealed housing and the flexible sealcombine to form a substantially sealed enclosure encasing the motor, therotating output shaft, the proximal end of the nutating shaft and thecentral bearing. cl Example 2A

The assembly of example 1A, wherein flexible seal is substantially fixedto the sealed housing and the nutating shaft.

Example 3A

The assembly of example 1A, wherein the nutating shaft is configured toonly nutate and not rotate substantially when motor operates to rotatethe rotating output shaft.

Example 4A

The assembly of example 1A, wherein the central bearing includes aradial spherical bearing.

Example 5A

The assembly of example 1A, wherein the flexible seal includes a metalbellows.

Example 6A

The assembly of example 5A, wherein the metal bellows includes anelectroformed metal bellows.

Example 7A

The assembly of example 5A, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and thenutating shaft.

Example 8A

The assembly of example 1A, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motor,the rotating output shaft, the proximal end of the nutating shaft andthe central bearing.

Example 9A

The assembly of example 1A, further comprising a mechanically adjustablemedical lead, the mechanically adjustable medical lead including arotatable member mechanically connected to a distal end of the nutatingshaft, wherein operation of the motor to rotate the rotating outputshaft rotates the rotatable member of the mechanically adjustablemedical lead to move a position of an electrode of the mechanicallyadjustable medical lead to adjust a spacing between a proximal end ofthe medical lead body and the electrode.

Example 10A

The assembly of example 1A, further comprising a mechanically adjustablemedical lead, the mechanically adjustable medical lead including arotatable member mechanically connected to a distal end of the nutatingshaft, wherein operation of the motor to rotate the rotating outputshaft rotates the rotatable member of the mechanically adjustablemedical lead to move a radial orientation an electrode of themechanically adjustable medical lead.

Example 11A

A method of adjusting a mechanically adjustable medical lead, whereinthe mechanically adjustable medical lead includes an electrode and arotatable member, the rotatable member being mechanically coupled to theelectrode, the method comprising operating a motor within a hermeticallysealed enclosure to drive the rotatable member of the medical lead andmove a position of the electrode to adjust a spacing between a proximalend of the medical lead and the electrode.

Example 12A

The method of example 11A, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 13A

The method of example 11A, wherein the mechanically adjustable medicallead further includes: an elongated medical lead body, wherein theelectrode is located at a distal portion of the medical lead body andthe rotatable member positioned adjacent to the proximal end of themedical lead body; and an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to the proximal end of the medical leadbody.

Example 14A

The method of example 11A, wherein the motor and the medical lead arepart of an assembly, wherein the assembly further comprises: a sealedhousing, wherein the motor is within the sealed housing, the motorincluding a rotating output shaft; a nutating shaft, wherein a proximalend of the nutating shaft is coupled to the rotating output shaft andwithin the sealed housing; a central bearing passing through the sealedhousing and supporting a central portion of the nutating shaft andwithin the sealed housing; and a flexible seal, a proximal side of theflexible seal covering a distal side of the central bearing, and adistal side of the flexible seal being secured to a distal portion ofthe nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form thehermetically sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 15A

The method of example 14A, wherein flexible seal is substantially fixedto the sealed housing and the nutating shaft.

Example 16A

The method of example 14A, wherein the nutating shaft is configured toonly nutate and not rotate substantially when motor operates to rotatethe rotating output shaft.

Example 17A

The method of example 14A, wherein the central bearing includes a radialspherical bearing.

Example 18A

The method of example 14A, wherein the flexible seal includes a metalbellows.

Example 19A

The method of example 18A, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and thenutating shaft.

Example 20A

A method of manufacture comprising: mechanically coupling a rotatingoutput shaft of a motor within a sealed housing to a proximal end of anutating shaft, wherein the nutating shaft is supported by a centralbearing passing through the sealed housing and supporting a centralportion of the nutating shaft and within the sealed housing; forming afirst hermetic seal at an interface between the sealed housing and aflexible seal, a proximal side of the flexible seal covering a distalside of the central bearing; and forming a second hermetic seal at aninterface between a distal portion of the nutating shaft locateddistally relative to the central bearing and a distal side of theflexible seal, wherein the sealed housing, the flexible seal, the firsthermetic seal and the second hermetic seal combine to form ahermetically sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 21A

The method of example 20A, wherein the flexible seal includes a metalbellows.

Example 22A

The method of example 21A, further comprising electroforming the metalbellows.

Example 23A

The method of example 20A, further comprising mechanically coupling adistal end of the nutating shaft to a rotatable member of a mechanicallyadjustable medical lead, wherein nutation of the nutating shaft isconfigured to rotate the rotatable member of the mechanically adjustablemedical lead to move a position of an electrode of the mechanicallyadjustable medical lead to adjust a spacing between a proximal end ofthe medical lead and the electrode.

Example 24A

The method of example 20A, further comprising mechanically coupling adistal end of the nutating shaft to a rotatable member of a mechanicallyadjustable medical lead, wherein nutation of the nutating shaft isconfigured to rotate the rotatable member of the mechanically adjustablemedical lead to move a radial orientation an electrode of themechanically adjustable medical lead.

Example 1B

A mechanically adjustable medical lead comprising: an elongated medicallead body; a retractable electrode located within a distal portion ofthe medical lead body; an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to a proximal end of the medical leadbody; and a rotatable member positioned adjacent to the proximal end ofthe medical lead body, wherein rotation of the rotatable member moves aposition of the retractable electrode to selectively deploy and retractthe retractable electrode from the medical lead body.

Example 2B

The medical lead of example 1B, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe rotatable member into substantially linear movement to move theposition of the retractable electrode.

Example 3B

The medical lead of example 1B, wherein the rotatable member is a firstrotatable member, the mechanically adjustable medical lead furthercomprising a second rotatable member positioned adjacent to the proximalend of the medical lead body, wherein rotation of the second rotatablemember varies an overall length of the medical lead.

Example 4B

The medical lead of example 3B, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe second rotatable member to vary the overall length of the medicallead.

Example 5B

The medical lead of example 1B, wherein the retractable electrode is afirst electrode, the insulated conductor is a first insulated conductorand the rotatable member is a first rotatable member, the mechanicallyadjustable medical lead further comprising: a second electrode locatedadjacent a distal end of the medical lead body; a third electrodelocated more proximally along the medical lead body as compared to thesecond electrode; a second insulated conductor extending within themedical lead body, the second insulated conductor being in electricalcontact with the second electrode and extending to the proximal end ofthe medical lead body; a third insulated conductor extending within themedical lead body, the third insulated conductor being in electricalcontact with the third electrode and extending to the proximal end ofthe medical lead body; a second rotatable member positioned adjacent tothe proximal end of the medical lead body, wherein rotation of thesecond rotatable member moves a position of the third electrode alongthe medical lead body to adjust a spacing between the second electrodeand the third electrode.

Example 6B

The medical lead of example 5B, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe second rotatable member into substantially linear movement to movethe position of the third electrode.

Example 7B

The medical lead of example 1B, wherein the medical lead body has asubstantially circular cross-sectional shape.

Example 8B

The medical lead of example 1B, wherein the medical lead comprises adeep brain stimulation (DBS) medical lead.

Example 9B

An assembly comprising: a motor including a rotating output shaft; and amechanically adjustable medical lead, the mechanically adjustablemedical lead comprising: an elongated medical lead body; a retractableelectrode located within a distal portion of the medical lead body; aninsulated conductor extending within the medical lead body, theinsulated conductor being in electrical contact with the retractableelectrode and extending to a proximal end of the medical lead body; anda rotatable member positioned adjacent to the proximal end of themedical lead body, wherein the rotatable member is mechanically coupledto and configured to be driven by the rotating output shaft of themotor, wherein rotation of the rotatable member moves a position of theretractable electrode to selectively deploy and retract the retractableelectrode from the medical lead body.

Example 10B

The assembly of example 9B, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of therotatable member into substantially linear movement to move the positionof the retractable electrode.

Example 11B

The assembly of example 9B, wherein the rotatable member is a firstrotatable member, the mechanically adjustable medical lead furthercomprising a second rotatable member positioned adjacent to the proximalend of the medical lead body, wherein rotation of the second rotatablemember varies an overall length of the medical lead.

Example 12B

The assembly of example 11B, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of the secondrotatable member to vary the overall length of the medical lead.

Example 13B

The assembly of example 9B, wherein the retractable electrode is a firstelectrode, the insulated conductor is a first insulated conductor andthe rotatable member is a first rotatable member, the mechanicallyadjustable medical lead further comprising: a second electrode locatedadjacent a distal end of the medical lead body; a third electrodelocated more proximally along the medical lead body as compared to thesecond electrode; a second insulated conductor extending within themedical lead body, the second insulated conductor being in electricalcontact with the second electrode and extending to the proximal end ofthe medical lead body; a third insulated conductor extending within themedical lead body, the third insulated conductor being in electricalcontact with the third electrode and extending to the proximal end ofthe medical lead body; a second rotatable member positioned adjacent tothe proximal end of the medical lead body, wherein rotation of thesecond rotatable member moves a position of the third electrode alongthe medical lead body to adjust a spacing between the second electrodeand the third electrode.

Example 14B

The assembly of example 13B, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of the secondrotatable member into substantially linear movement to move the positionof the third electrode.

Example 15B

The assembly of example 9B, further comprising: a sealed housing, themotor being within the sealed housing; a nutating shaft, wherein aproximal end of the nutating shaft is coupled to the rotating outputshaft and within the sealed housing; a central bearing passing throughthe sealed housing and supporting a central portion of the nutatingshaft and within the sealed housing; and a flexible seal, a proximalside of the flexible seal covering a distal side of the central bearing,and a distal side of the flexible seal being secured to a distal portionof the nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form asubstantially sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 16B

The assembly of example 15B, wherein the flexible seal includes a metalbellows.

Example 17B

The assembly of example 15B, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motor,the rotating output shaft, the proximal end of the nutating shaft andthe central bearing.

Example 18B

The assembly of example 9B, further comprising a stimulation generatorconfigured to deliver electrical stimulation via the electrode of themedical lead, wherein the stimulation generator is electrically coupledto the electrode of the medical lead.

Example 19B

A method comprising operating a motor to drive a rotating output shaftof a motor and deploy a retractable electrode of a mechanicallyadjustable medical lead, wherein the mechanically adjustable medicallead comprises: an elongated medical lead body; the retractableelectrode, the retractable electrode being extendable from a distalportion of the medical lead body; an insulated conductor extendingwithin the medical lead body, the insulated conductor being inelectrical contact with the retractable electrode and extending to aproximal end of the medical lead body; and a rotatable member positionedadjacent to the proximal end of the medical lead body, wherein therotatable member is mechanically coupled to and configured to be drivenby the rotating output shaft of the motor, wherein rotation of therotatable member moves a position of the retractable electrode toselectively deploy and retract the retractable electrode from themedical lead body.

Example 20B

The method of example 19B, further comprising operating the motor todrive the rotating output shaft of the motor and retract the deployedretractable electrode of the mechanically adjustable medical lead.

Example 21B

The method of example 19B, further comprising, delivering, via asimulation generator, electrical simulation to a patient via thedeployed retractable electrode.

Example 22B

The method of example 19B, further comprising, sensing a physiologicalcondition of a patient via the deployed retractable electrode.

Example 23B

The method of example 19B, further comprising receiving a force signalfrom a force sensor, the force signal representing a resistance tomovement of a position of the retractable electrode of the medical lead,wherein operating the motor to drive the rotating output shaft of themotor and deploy the retractable electrode of the mechanicallyadjustable medical lead is based on the force signal.

Example 24B

The method of example 23B, wherein operating the motor to drive therotating output shaft of the motor and deploy the retractable electrodeof the mechanically adjustable medical lead includes limiting movementof the retractable electrode to prevent resistance to the movement ofthe retractable electrode from exceeding a predefined value.

Example 1C

An assembly comprising: a motor including a rotating output shaft; and amechanically adjustable medical lead, the mechanically adjustablemedical lead comprising: an elongated medical lead body; an electrodelocated at a distal portion of the medical lead body; an insulatedconductor extending within the medical lead body, the insulatedconductor being in electrical contact with the electrode and extendingto a proximal end of the medical lead body; and a rotatable memberpositioned adjacent to the proximal end of the medical lead body,wherein the rotatable member is mechanically coupled to and configuredto be driven by the rotating output shaft of the motor such thatrotation of the rotatable member moves a position of the electrode toadjust a spacing between the proximal end of the medical lead body andthe electrode.

Example 2C

The assembly of example 1C, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of therotatable member into substantially linear movement to move the positionof the electrode.

Example 3C

The assembly of example 1C, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 4C

The assembly of example 3C, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of therotatable member into substantially linear movement to vary the overalllength of the medical lead.

Example 5C

The assembly of example 1C, wherein the electrode is a first electrode,the insulated conductor is a first insulated conductor and the rotatablemember is a first rotatable member, the mechanically adjustable medicallead further comprising: a second electrode located more proximallyalong the medical lead body as compared to the first electrode; a secondinsulated conductor extending within the medical lead body, the secondinsulated conductor being in electrical contact with the secondelectrode and extending to the proximal end of the medical lead body; asecond rotatable member positioned adjacent to the proximal end of themedical lead body, wherein rotation of the second rotatable member movesa position of the second electrode along the medical lead body to adjusta spacing between the first electrode and the second electrode.

Example 6C

The assembly of example 5C, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of the secondrotatable member into substantially linear movement to move the positionof the second electrode.

Example 7C

The assembly of example 5C, wherein the first electrode is positionedadjacent a distal end of the medical lead and rotation of the firstrotatable member varies an overall length of the medical lead.

Example 8C

The assembly of example 1C, further comprising: a sealed housing, themotor being within the sealed housing; a nutating shaft, wherein aproximal end of the nutating shaft is coupled to the rotating outputshaft and within the sealed housing; a central bearing passing throughthe sealed housing and supporting a central portion of the nutatingshaft and within the sealed housing; and a flexible seal, a proximalside of the flexible seal covering a distal side of the central bearing,and a distal side of the flexible seal being secured to a distal portionof the nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form asubstantially sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 9C

The assembly of example 8C, wherein the nutating shaft is configured toonly nutate and not rotate substantially when the motor operates torotate the rotating output shaft.

Example 10C

The assembly of example 8C, wherein the central bearing includes aradial spherical bearing.

Example 11C

The assembly of example 8C, wherein the flexible seal includes a metalbellows.

Example 12C

The assembly of example 8C, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motor,the rotating output shaft, the proximal end of the nutating shaft andthe central bearing.

Example 13C

The assembly of example 1C, further comprising a stimulation generatorconfigured to deliver electrical stimulation via the electrode of themedical lead, wherein the stimulation generator is electrically coupledto the electrode of the medical lead via the conductor.

Example 14C

A mechanically adjustable medical lead comprising: an elongated medicallead body; a first electrode located at a distal portion of the medicallead body; a first insulated conductor extending within the medical leadbody, the first insulated conductor being in electrical contact with thefirst electrode and extending to a proximal end of the medical leadbody; a second electrode located more proximally along the medical leadbody as compared to the first electrode; a second insulated conductorextending within the medical lead body, the second insulated conductorbeing in electrical contact with the second electrode and extending tothe proximal end of the medical lead body; and a rotatable memberpositioned adjacent to the proximal end of the medical lead body,wherein rotation of the rotatable member moves a position of the secondelectrode along the medical lead body to adjust a spacing between thefirst electrode and the second electrode.

Example 15C

The medical lead of example 14C, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe rotatable member into substantially linear movement to move theposition of the second electrode.

Example 16C

The medical lead of example 14C, wherein the rotatable member is a firstrotatable member, the mechanically adjustable medical lead furthercomprising a second rotatable member positioned adjacent to the proximalend of the medical lead body, wherein rotation of the second rotatablemember varies an overall length of the medical lead.

Example 17C

The medical lead of example 16C, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe second rotatable member into substantially linear movement to varythe overall length of the medical lead.

Example 18C

The medical lead of example 14C, further comprising: a sealed housing, amotor being within the sealed housing and including a rotating outputshaft; a nutating shaft, wherein a proximal end of the nutating shaft iscoupled to the rotating output shaft and within the sealed housing; acentral bearing passing through the sealed housing and supporting acentral portion of the nutating shaft and within the sealed housing; anda flexible seal, a proximal side of the flexible seal covering a distalside of the central bearing, and a distal side of the flexible sealbeing secured to a distal portion of the nutating shaft located distallyrelative to the central bearing, wherein the sealed housing and theflexible seal combine to form a substantially sealed enclosure encasingthe motor, the rotating output shaft, the proximal end of the nutatingshaft and the central bearing.

Example 19C

The medical lead of example 18C, wherein the nutating shaft isconfigured to only nutate and not rotate substantially when motoroperates to rotate the rotating output shaft.

Example 20C

The medical lead of example 18C, wherein the central bearing includes aradial spherical bearing.

Example 21C

The medical lead of example 18C, wherein the flexible seal includes ametal bellows.

Example 22C

The medical lead of example 21C, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and thenutating shaft.

Example 23C

The medical lead of example 18C, wherein the sealed housing and theflexible seal combine to form a hermetically sealed enclosure encasingthe motor, the rotating output shaft, the proximal end of the nutatingshaft and the central bearing.

Example 24C

The medical lead of example 14C, further comprising a stimulationgenerator configured to deliver electrical stimulation via the electrodeof the medical lead, wherein the stimulation generator is electricallycoupled to the electrode of the medical lead via the first insulatedconductor.

Example 25C

The medical lead of example 14C, wherein the medical lead body has asubstantially circular cross-sectional shape.

Example 26C

The medical lead of example 14C, wherein the medical lead comprises adeep brain stimulation (DBS) medical lead.

Example 27C

A method comprising: operating a motor to drive a rotating output shaftof a motor and move a position of an electrode of a mechanicallyadjustable medical lead, wherein the mechanically adjustable medicallead comprises: an elongated medical lead body; the electrode, theelectrode being located at a distal portion of the medical lead body; aninsulated conductor extending within the medical lead body, theinsulated conductor being in electrical contact with the electrode andextending to a proximal end of the medical lead body; and a rotatablemember positioned adjacent to the proximal end of the medical lead body,wherein the rotatable member is mechanically coupled to and configuredto be driven by the rotating output shaft of the motor, wherein rotationof the rotatable member moves the position of the electrode to adjust aspacing between the proximal end of the medical lead body and theelectrode.

Example 28C

The method of example 27C, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 29C

The method of example 27C, wherein the motor is a first motor, whereinthe electrode is a first electrode, the insulated conductor is a firstinsulated conductor and the rotatable member is a first rotatablemember, the mechanically adjustable medical lead further comprising:second electrode located more proximally along the medical lead body ascompared to the first electrode; a second insulated conductor extendingwithin the medical lead body, the second insulated conductor being inelectrical contact with the second electrode and extending to theproximal end of the medical lead body; a second rotatable memberpositioned adjacent to the proximal end of the medical lead body, themethod further comprising operating a second motor to drive the secondrotatable member of the medical lead to move a position of the secondelectrode along the medical lead body to adjust a spacing between thefirst electrode and the second electrode.

Example 30

The method of example 27C, wherein the motor and the medical lead areincluded within an assembly, the assembly further comprising: a sealedhousing, the motor being within the sealed housing; a nutating shaft,wherein a proximal end of the nutating shaft is coupled to the rotatingoutput shaft and within the sealed housing; a central bearing passingthrough the sealed housing and supporting a central portion of thenutating shaft and within the sealed housing; and a flexible seal, aproximal side of the flexible seal covering a distal side of the centralbearing, and a distal side of the flexible seal being secured to adistal portion of the nutating shaft located distally relative to thecentral bearing, wherein the sealed housing and the flexible sealcombine to form a substantially sealed enclosure encasing the motor, therotating output shaft, the proximal end of the nutating shaft and thecentral bearing.

Example 31C

A method of adjusting a mechanically adjustable medical lead, whereinthe mechanically adjustable medical lead includes an electrode and arotatable member, the rotatable member being mechanically coupled to theelectrode, the method comprising: monitoring a physiological conditionof a patient; and operating, based on the monitored physiologicalcondition, a motor to drive the rotatable member of the medical lead viaa rotating output shaft of the motor and move a position of theelectrode to adjust a position of the electrode.

Example 32C

The method of example 31C, monitoring the physiological condition of thepatient includes monitoring the physiological condition of the patientvia the electrode.

Example 33C

The method of example 31C, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 34C

The method of example 31C, wherein the mechanically adjustable medicallead further includes: an elongated medical lead body, wherein theelectrode is located at a distal portion of the medical lead body andthe rotatable member positioned adjacent to the proximal end of themedical lead body; and an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to the proximal end of the medical leadbody.

Example 35C

The method of example 34C, wherein the motor is a first motor, whereinthe electrode is a first electrode, the insulated conductor is a firstinsulated conductor and the rotatable member is a first rotatablemember, the mechanically adjustable medical lead further comprising: asecond electrode located more proximally along the medical lead body ascompared to the first electrode; a second insulated conductor extendingwithin the medical lead body, the second insulated conductor being inelectrical contact with the second electrode and extending to theproximal end of the medical lead body; a second rotatable memberpositioned adjacent to the proximal end of the medical lead body, themethod further comprising operating, based on the physiologicalcondition, a second motor to drive the second rotatable member of themedical lead to move a position of the second electrode along themedical lead body to adjust a spacing between the first electrode andthe second electrode.

Example 36C

The method of example 31C, wherein the motor and the medical lead areincluded within an assembly, the assembly further comprising: a sealedhousing, the motor being within the sealed housing; a nutating shaft,wherein a proximal end of the nutating shaft is coupled to the rotatingoutput shaft and within the sealed housing; a central bearing passingthrough the sealed housing and supporting a central portion of thenutating shaft and within the sealed housing; and a flexible seal, aproximal side of the flexible seal covering a distal side of the centralbearing, and a distal side of the flexible seal being secured to adistal portion of the nutating shaft located distally relative to thecentral bearing, wherein the sealed housing and the flexible sealcombine to form a substantially sealed enclosure encasing the motor, therotating output shaft, the proximal end of the nutating shaft and thecentral bearing.

Example 37C

The method of example 31C, wherein the physiological condition includesone or more of a group consisting of: patient brain signals; patientactivity level; patient posture; patient tremors; and patient sleepcharacteristics.

Example 38C

The method of example 31C, further comprising selecting the position ofthe electrode based on the monitored physiological condition of thepatient to enhance either the detection of the monitored physiologicalcondition of the patient or improve the efficacy of a therapy deliveredvia the electrode.

Example 39C

The method of example 31C, wherein operating the motor to drive therotatable member of the medical lead adjusts a spacing between aproximal end of the medical lead and the electrode.

Example 1D

An assembly comprising: a processor; a motor including a rotating outputshaft; a mechanically adjustable medical lead including an electrode, amedical lead body, an insulated conductor extending within the medicallead body, the insulated conductor being in electrical contact with theelectrode and extending to a proximal end of the medical lead body, anda rotatable member, the rotatable member being mechanically coupled tothe electrode, wherein rotation of the rotating output shaft rotates therotatable member of the medical lead to move a position of the electrodeto adjust a spacing between a proximal end of the medical lead and theelectrode; and a force sensor configured to measure a resistance tomovement of the position of the electrode and deliver a force signal tothe processor based on the resistance to movement of the position of theelectrode, wherein the processor is configured to operate the motor toadjust the spacing between the proximal end of the medical lead body andthe electrode based on the force signal from the force sensor.

Example 2D

The assembly of example 1D, wherein the mechanically adjustable medicallead further includes: an elongated medical lead body, wherein theelectrode is located at a distal portion of the medical lead body andthe rotatable member positioned adjacent to the proximal end of themedical lead body; and an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to the proximal end of the medical leadbody.

Example 3D

The assembly of example 1D, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of therotatable member into substantially linear movement to move the positionof the electrode.

Example 4D

The assembly of example 1D, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 5D

The assembly of example 4D, wherein the mechanically adjustable medicallead includes a threaded joint that transfers the rotation of therotatable member into substantially linear movement to vary the overalllength of the medical lead.

Example 6D

The assembly of example 1D, wherein the electrode is a first electrode,the insulated conductor is a first insulated conductor and the rotatablemember is a first rotatable member, the mechanically adjustable medicallead further comprising: a second electrode located more proximallyalong the medical lead body as compared to the first electrode; a secondinsulated conductor extending within the medical lead body, the secondinsulated conductor being in electrical contact with the secondelectrode and extending to the proximal end of the medical lead body; asecond rotatable member positioned adjacent to the proximal end of themedical lead body, wherein rotation of the second rotatable member movesa position of the second electrode along the medical lead body to adjusta spacing between the first electrode and the second electrode.

Example 7D

The assembly of example 6D, wherein the first electrode is positionedadjacent a distal end of the medical lead and rotation of the firstrotatable member varies an overall length of the medical lead.

Example 8D

The assembly of example 1D, further comprising: a sealed housing, themotor being within the sealed housing; a nutating shaft, wherein aproximal end of the nutating shaft is coupled to the rotating outputshaft and within the sealed housing; a central bearing passing throughthe sealed housing and supporting a central portion of the nutatingshaft and within the sealed housing; and a flexible seal, a proximalside of the flexible seal covering a distal side of the central bearing,and a distal side of the flexible seal being secured to a distal portionof the nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form asubstantially sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 9D

The assembly of example 8D, wherein the flexible seal includes a metalbellows.

Example 10D

The assembly of example 8D, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motor,the rotating output shaft, the proximal end of the nutating shaft andthe central bearing.

Example 11D

The assembly of example 1D, further comprising a stimulation generatorconfigured to deliver electrical stimulation via the electrode of themedical lead, wherein the stimulation generator is electrically coupledto the electrode of the medical lead.

Example 12D

The assembly of example 1D, wherein the processor is configured tooperate the motor to adjust the spacing between the proximal end of themedical lead body and the electrode based on the force signal from theforce sensor at least in part by limiting movement of the position ofthe electrode to prevent the resistance to movement of the position ofthe electrode from exceeding a predefined value.

Example 13D

The assembly of example 1D, wherein the force sensor includes apiezoelectric sensor.

Example 14D

A mechanically adjustable medical lead comprising: an elongated medicallead body; a first electrode located at a distal portion of the medicallead body; a first insulated conductor extending within the medical leadbody, the first insulated conductor being in electrical contact with thefirst electrode and extending to a proximal end of the medical leadbody; a second electrode located more proximally along the medical leadbody as compared to the first electrode; a second insulated conductorextending within the medical lead body, the second insulated conductorbeing in electrical contact with the second electrode and extending tothe proximal end of the medical lead body; a rotatable member positionedadjacent to the proximal end of the medical lead body, wherein rotationof the rotatable member moves a position of the second electrode alongthe medical lead body to adjust a spacing between the first electrodeand the second electrode; and a force sensor configured to measure aresistance to movement of the position of the second electrode anddeliver a force signal to a processor based on the resistance tomovement of the position of the second electrode.

Example 15D

The medical lead of example 14D, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe rotatable member into substantially linear movement to move theposition of the second electrode.

Example 16D

The medical lead of example 14D, wherein the rotatable member is a firstrotatable member, the mechanically adjustable medical lead furthercomprising a second rotatable member positioned adjacent to the proximalend of the medical lead body, wherein rotation of the second rotatablemember varies an overall length of the medical lead.

Example 17D

The medical lead of example 16D, wherein the mechanically adjustablemedical lead includes a threaded joint that transfers the rotation ofthe second rotatable member into substantially linear movement to varythe overall length of the medical lead.

Example 18D

The medical lead of example 14D, further comprising: a sealed housing, amotor being within the sealed housing and including a rotating outputshaft; a nutating shaft, wherein a proximal end of the nutating shaft iscoupled to the rotating output shaft and within the sealed housing; acentral bearing passing through the sealed housing and supporting acentral portion of the nutating shaft and within the sealed housing; anda flexible seal, a proximal side of the flexible seal covering a distalside of the central bearing, and a distal side of the flexible sealbeing secured to a distal portion of the nutating shaft located distallyrelative to the central bearing, wherein the sealed housing and theflexible seal combine to form a substantially sealed enclosure encasingthe motor, the rotating output shaft, the proximal end of the nutatingshaft and the central bearing.

Example 19D

The medical lead of example 18D, wherein the flexible seal includes ametal bellows.

Example 20D

The medical lead of example 18D, wherein the sealed housing and theflexible seal combine to form a hermetically sealed enclosure encasingthe motor, the rotating output shaft, the proximal end of the nutatingshaft and the central bearing.

Example 21D

The medical lead of example 14D, further comprising a stimulationgenerator configured to deliver electrical stimulation via the electrodeof the medical lead, wherein the stimulation generator is electricallycoupled to the electrode of the medical lead.

Example 22D

The medical lead of example 14D, wherein the medical lead body has asubstantially circular cross-sectional shape.

Example 23D

The medical lead of example 14D, wherein the medical lead comprises adeep brain stimulation (DBS) medical lead.

Example 24D

The medical lead of example 14D, wherein the force sensor includes apiezoelectric sensor.

Example 25D

A method of adjusting a mechanically adjustable medical lead, whereinthe mechanically adjustable medical lead includes an electrode and arotatable member, the rotatable member being mechanically coupled to theelectrode, the method comprising: receiving a force signal from a forcesensor, the force signal representing a resistance to movement of theposition of the electrode of the medical lead; and operating, based onthe force signal, a motor to drive the rotatable member of the medicallead via a rotating output shaft of the motor and move a position of theelectrode to adjust a spacing between a proximal end of the medical leadand the electrode.

Example 26D

The method of example 25D, wherein operating, based on the force signal,the motor to drive the rotatable member of the medical lead and move theposition of the electrode to adjust the spacing between the proximal endof the medical lead and the electrode includes limiting movement of theposition of the electrode to prevent resistance to movement of theposition of the electrode from exceeding a predefined value.

Example 27D

The method of example 25D, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 28D

The method of example 25D, wherein the mechanically adjustable medicallead further includes: an elongated medical lead body, wherein theelectrode is located at a distal portion of the medical lead body andthe rotatable member positioned adjacent to the proximal end of themedical lead body; and an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to the proximal end of the medical leadbody.

Example 29D

The method of example 28D, wherein the electrode is a first electrode,the insulated conductor is a first insulated conductor and the rotatablemember is a first rotatable member, the mechanically adjustable medicallead further comprising: a second electrode located more proximallyalong the medical lead body as compared to the first electrode; a secondinsulated conductor extending within the medical lead body, the secondinsulated conductor being in electrical contact with the secondelectrode and extending to the proximal end of the medical lead body; asecond rotatable member positioned adjacent to the proximal end of themedical lead body, the method further comprising: mechanically couplingthe motor to the second rotatable member; and operating, based on theforce signal, the motor to drive the second rotatable member of themedical lead to move a position of the second electrode along themedical lead body to adjust a spacing between the first electrode andthe second electrode.

Example 30D

The method of example 25D, wherein the motor and the medical lead areincluded within an assembly, the assembly further comprising: a sealedhousing, the motor being within the sealed housing; a nutating shaft,wherein a proximal end of the nutating shaft is coupled to the rotatingoutput shaft and within the sealed housing; a central bearing passingthrough the sealed housing and supporting a central portion of thenutating shaft and within the sealed housing; and a flexible seal, aproximal side of the flexible seal covering a distal side of the centralbearing, and a distal side of the flexible seal being secured to adistal portion of the nutating shaft located distally relative to thecentral bearing, wherein the sealed housing and the flexible sealcombine to form a substantially sealed enclosure encasing the motor, therotating output shaft, the proximal end of the nutating shaft and thecentral bearing.

Example 1E

An assembly comprising: a sealed housing; a motor within the sealedhousing, the motor including a rotating output shaft; a first coaxialshaft within the sealed housing, the first coaxial shaft beingmechanically coupled to the rotating output shaft such that rotation ofthe rotating output shaft drives rotation of the first coaxial shaft; asecond coaxial shaft external to the sealed housing, the second coaxialshaft being in axial alignment with the first coaxial shaft; an offsetpin mechanically coupling the first coaxial shaft to the second coaxialshaft, wherein rotation of the rotating first coaxial shaft drives acircular motion of the offset pin about the axis of the first coaxialshaft, wherein the circular motion of the offset pin drives rotation ofthe second coaxial shaft; and a flexible seal including an oscillatingcap, the oscillating cap being mechanically coupled to the offset pinsuch that the oscillating cap oscillates in unison with the circularmotion of the offset pin, wherein the sealed housing and the flexibleseal combine to form a substantially sealed enclosure encasing the motorand the first coaxial shaft.

Example 2E

The assembly of example 1E, further comprising: a first bearing betweenthe first coaxial shaft and the oscillating cap; and a second bearingbetween the first coaxial shaft and the offset pin, wherein the firstand second bearing combine to allow the oscillating cap to oscillatewithout rotating while the first coaxial shaft and the second coaxialshaft rotate.

Example 3E

The assembly of example 2E, wherein the offset pin and the oscillatingcap are fixed relative to one another as a functionally unitarycomponent, wherein the first bearing is between the first coaxial shaftand the unitary component, and wherein the second bearing is between thesecond coaxial shaft and the unitary component.

Example 4E

The assembly of example 2E, wherein the offset pin and the secondcoaxial shaft are fixed relative to one another as a functionallyunitary component, wherein the first bearing is between the firstcoaxial shaft and the oscillating cap, and wherein the second bearing isbetween the oscillating cap and the unitary component.

Example 5E

The assembly of example 2E, wherein the offset pin and the first coaxialshaft are fixed relative to one another as a functionally unitarycomponent, wherein the first bearing is between the unitary componentand the oscillating cap, and wherein the second bearing is between theoscillating cap and the second coaxial shaft.

Example 6E

The assembly of example 1E, wherein the flexible seal includes a metalbellows.

Example 7E

The assembly of example 6E, wherein the metal bellows includes anelectroformed metal bellows.

Example 8E

The assembly of example 6E, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and theoscillating cap.

Example 9E

The assembly of example 1E, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motorand the first coaxial shaft.

Example 10E

The assembly of example 1E, further comprising a mechanically adjustablemedical lead, the mechanically adjustable medical lead including arotatable member mechanically connected to a distal end of the secondcoaxial shaft, wherein operation of the motor to rotate the secondcoaxial shaft rotates the rotatable member of the mechanicallyadjustable medical lead to move a position of an electrode of themechanically adjustable medical lead to adjust a spacing between aproximal end of the medical lead body and the electrode.

Example 11E

The assembly of example 1E, further comprising a mechanically adjustablemedical lead, the mechanically adjustable medical lead including arotatable member mechanically connected to a distal end of the secondcoaxial shaft, wherein operation of the motor to rotate the rotatingoutput shaft rotates the rotatable member of the mechanically adjustablemedical lead to move a radial orientation an electrode of themechanically adjustable medical lead.

Example 12E

A method of manufacture for an assembly comprising: a sealed housing; amotor within the sealed housing, the motor including a rotating outputshaft; a first coaxial shaft within the sealed housing, the firstcoaxial shaft being mechanically coupled to the rotating output shaftsuch that rotation of the rotating output shaft drives rotation of thefirst coaxial shaft; a second coaxial shaft external to the sealedhousing, the second coaxial shaft being in axial alignment with thefirst coaxial shaft; an offset pin mechanically coupling the firstcoaxial shaft to the second coaxial shaft, wherein rotation of therotating first coaxial shaft drives a circular motion of the offset pinabout the axis of the first coaxial shaft, wherein the circular motionof the offset pin drives rotation of the second coaxial shaft; and aflexible seal including a flexible portion and an oscillating cap, theoscillating cap being mechanically coupled to the offset pin such thatthe oscillating cap oscillates in unison with the circular motion of theoffset pin, the method comprising: forming a first hermetic seal at aninterface between the oscillating cap and the flexible portion of theflexible seal; and forming a second hermetic seal at an interfacebetween the sealed housing and a flexible seal, wherein the sealedhousing, the flexible seal including the flexible portion and theoscillating cap, the first hermetic seal and the second hermetic sealcombine to form a hermetically sealed enclosure encasing the motor andthe first coaxial shaft.

Example 13E

The method of example 12E, wherein the flexible seal includes a metalbellows.

Example 14E

The method of example 13E, further comprising electroforming the metalbellows.

Example 15E

The method of example 12E, further comprising mechanically coupling adistal end of the second coaxial shaft to a rotatable member of amechanically adjustable medical lead, wherein rotation of the secondcoaxial shaft is configured to rotate the rotatable member of themechanically adjustable medical lead to move a position of an electrodeof the mechanically adjustable medical lead to adjust a spacing betweena proximal end of the medical lead and the electrode.

Example 16E

The method of example 12E, further comprising mechanically coupling adistal end of the second coaxial shaft a rotatable member of amechanically adjustable medical lead, wherein rotation of the secondcoaxial shaft is configured to rotate the rotatable member of themechanically adjustable medical lead to move a radial orientation anelectrode of the mechanically adjustable medical lead.

Example 17E

A method of adjusting a mechanically adjustable medical lead, whereinthe mechanically adjustable medical lead includes an electrode and arotatable member, the rotatable member being mechanically coupled to theelectrode, the method comprising operating a motor within a hermeticallysealed enclosure to drive the rotatable member of the medical lead andmove a position of the electrode to adjust a spacing between a proximalend of the medical lead and the electrode.

Example 18E

The method of example 17E, wherein the electrode is positioned adjacenta distal end of the medical lead and rotation of the rotatable membervaries an overall length of the medical lead.

Example 19E

The method of example 17E, wherein the mechanically adjustable medicallead further includes: an elongated medical lead body, wherein theelectrode is located at a distal portion of the medical lead body andthe rotatable member positioned adjacent to the proximal end of themedical lead body; and an insulated conductor extending within themedical lead body, the insulated conductor being in electrical contactwith the electrode and extending to the proximal end of the medical leadbody.

Example 20E

The method of example 17E, wherein the motor and the medical lead arepart of an assembly, wherein the assembly further comprises: a sealedhousing; a motor within the sealed housing, the motor including arotating output shaft; a first coaxial shaft within the sealed housing,the first coaxial shaft being mechanically coupled to the rotatingoutput shaft such that rotation of the rotating output shaft drivesrotation of the first coaxial shaft; a second coaxial shaft external tothe sealed housing, the second coaxial shaft being in axial alignmentwith the first coaxial shaft; an offset pin mechanically coupling thefirst coaxial shaft to the second coaxial shaft, wherein rotation of therotating first coaxial shaft drives a circular motion of the offset pinabout the axis of the first coaxial shaft, wherein the circular motionof the offset pin drives rotation of the second coaxial shaft; and aflexible seal including an oscillating cap, the oscillating cap beingmechanically coupled to the offset pin such that the oscillating caposcillates in unison with the circular motion of the offset pin, whereinthe sealed housing and the flexible seal combine to form thehermetically sealed enclosure encasing the motor and the first coaxialshaft.

Example 21E

The method of example 20E, wherein the flexible seal includes a metalbellows.

Example 22E

The method of example 21E, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and theoscillating cap.

Example 23E

The method of example 17E, wherein the motor and the medical lead arepart of an assembly, wherein the assembly further comprises: a sealedhousing, wherein the motor is within the sealed housing, the motorincluding a rotating output shaft; a nutating shaft, wherein a proximalend of the nutating shaft is coupled to the rotating output shaft andwithin the sealed housing; a central bearing passing through the sealedhousing and supporting a central portion of the nutating shaft andwithin the sealed housing; and a flexible seal, a proximal side of theflexible seal covering a distal side of the central bearing, and adistal side of the flexible seal being secured to a distal portion ofthe nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form thehermetically sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 24E

The method of example 23E, wherein flexible seal is substantially fixedto the sealed housing and the nutating shaft.

Example 25E

The method of example 23E, wherein the nutating shaft is configured toonly nutate and not rotate substantially when motor operates to rotatethe rotating output shaft.

Example 26E

The method of example 23E, wherein the central bearing includes a radialspherical bearing.

Example 27E

The method of example 23E, wherein the flexible seal includes a metalbellows.

Example 28E

The method of example 27E, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and thenutating shaft.

Example 29E

An assembly comprising: a sealed housing; a motor within the sealedhousing, the motor including a rotating output shaft; a nutating shaft,wherein a proximal end of the nutating shaft is coupled to the rotatingoutput shaft and within the sealed housing; a central bearing passingthrough the sealed housing and supporting a central portion of thenutating shaft and within the sealed housing; and a flexible seal, aproximal side of the flexible seal covering a distal side of the centralbearing, and a distal side of the flexible seal being secured to adistal portion of the nutating shaft located distally relative to thecentral bearing, wherein the sealed housing and the flexible sealcombine to form a substantially sealed enclosure encasing the motor, therotating output shaft, the proximal end of the nutating shaft and thecentral bearing.

Example 30E

The assembly of example 29E, wherein flexible seal is substantiallyfixed to the sealed housing and the nutating shaft.

Example 31E

The assembly of example 29E, wherein the nutating shaft is configured toonly nutate and not rotate substantially when motor operates to rotatethe rotating output shaft.

Example 32E

The assembly of example 29E, wherein the central bearing includes aradial spherical bearing.

Example 33E

The assembly of example 29E, wherein the flexible seal includes a metalbellows.

Example 34E

The assembly of example 33E, wherein the metal bellows includes anelectroformed metal bellows.

Example 35E

The assembly of example 33E, further comprising: a first weld jointsealing an interface of the metal bellows and the sealed housing; and asecond weld joint sealing an interface of the metal bellows and thenutating shaft.

Example 36E

The assembly of example 29E, wherein the sealed housing and the flexibleseal combine to form a hermetically sealed enclosure encasing the motor,the rotating output shaft, the proximal end of the nutating shaft andthe central bearing.

Example 37E

The assembly of example 29E, further comprising a mechanicallyadjustable medical lead, the mechanically adjustable medical leadincluding a rotatable member mechanically connected to a distal end ofthe nutating shaft, wherein operation of the motor to rotate therotating output shaft rotates the rotatable member of the mechanicallyadjustable medical lead to move a position of an electrode of themechanically adjustable medical lead to adjust a spacing between aproximal end of the medical lead body and the electrode.

Example 38E

The assembly of example 29E, further comprising a mechanicallyadjustable medical lead, the mechanically adjustable medical leadincluding a rotatable member mechanically connected to a distal end ofthe nutating shaft, wherein operation of the motor to rotate therotating output shaft rotates the rotatable member of the mechanicallyadjustable medical lead to move a radial orientation an electrode of themechanically adjustable medical lead.

Example 39E

A method of manufacture comprising: mechanically coupling a rotatingoutput shaft of a motor within a sealed housing to a proximal end of anutating shaft, wherein the nutating shaft is supported by a centralbearing passing through the sealed housing and supporting a centralportion of the nutating shaft and within the sealed housing; forming afirst hermetic seal at an interface between the sealed housing and aflexible seal, a proximal side of the flexible seal covering a distalside of the central bearing; and forming a second hermetic seal at aninterface between a distal portion of the nutating shaft locateddistally relative to the central bearing and a distal side of theflexible seal, wherein the sealed housing, the flexible seal, the firsthermetic seal and the second hermetic seal combine to form ahermetically sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.

Example 40E

The method of example 39E, wherein the flexible seal includes a metalbellows.

Example 41E

The method of example 39E, further comprising electroforming the metalbellows.

Example 42E

The method of example 39E, further comprising mechanically coupling adistal end of the nutating shaft to a rotatable member of a mechanicallyadjustable medical lead, wherein nutation of the nutating shaft isconfigured to rotate the rotatable member of the mechanically adjustablemedical lead to move a position of an electrode of the mechanicallyadjustable medical lead to adjust a spacing between a proximal end ofthe medical lead and the electrode.

Example 43E

The method of example 39E, further comprising mechanically coupling adistal end of the nutating shaft to a rotatable member of a mechanicallyadjustable medical lead, wherein nutation of the nutating shaft isconfigured to rotate the rotatable member of the mechanically adjustablemedical lead to move a radial orientation an electrode of themechanically adjustable medical lead.

Various examples have been described, and, when possible, combinationsof these examples are contemplated. However, modifications may be madeto the described examples within the spirit of the present disclosure.These and other examples are within the scope of the following claims.

What is claimed is:
 1. An implantable medical device assemblycomprising: a sealed housing; a motor within the sealed housing, themotor including a rotating output shaft; a first coaxial shaft withinthe sealed housing, the first coaxial shaft being mechanically coupledto the rotating output shaft such that rotation of the rotating outputshaft drives rotation of the first coaxial shaft; a second coaxial shaftexternal to the sealed housing, the second coaxial shaft being in axialalignment with the first coaxial shaft; an oscillating componentmechanically coupling the first coaxial shaft to the second coaxialshaft, wherein rotation of the rotating first coaxial shaft drives theoscillation of the oscillating component, wherein the oscillation of theoscillating component drives rotation of the second coaxial shaft; and aflexible seal including the oscillating component, wherein the sealedhousing and the flexible seal combine to form a substantially sealedenclosure encasing the motor and the first coaxial shaft.
 2. Theimplantable medical device assembly of claim 1, further comprising anoffset pin mechanically coupling the first coaxial shaft to the secondcoaxial shaft, wherein rotation of the rotating first coaxial shaftdrives a circular motion of the offset pin about the axis of the firstcoaxial shaft, wherein the circular motion of the offset pin drivesrotation of the second coaxial shaft; wherein the oscillating componentis an oscillating cap, the oscillating cap being mechanically coupled tothe offset pin such that the oscillating cap oscillates in unison withthe circular motion of the offset pin,
 3. The implantable medical deviceassembly of claim 2, further comprising: a first bearing between thefirst coaxial shaft and the oscillating cap; and a second bearingbetween the first coaxial shaft and the offset pin, wherein the firstand second bearing combine to allow the oscillating cap to oscillatewithout rotating while the first coaxial shaft and the second coaxialshaft rotate.
 4. The implantable medical device assembly of claim 1,wherein the oscillating component is a nutating shaft, wherein aproximal end of the nutating shaft is coupled to the rotating outputshaft and within the sealed housing, wherein the assembly furthercomprises a central bearing passing through the sealed housing andsupporting a central portion of the nutating shaft and within the sealedhousing, wherein a proximal side of the flexible seal covers a distalside of the central bearing, wherein a distal side of the flexible sealis secured to a distal portion of the nutating shaft located distallyrelative to the central bearing, wherein the substantially sealedenclosure formed by the sealed housing and the flexible seal encases themotor, the rotating output shaft, the proximal end of the nutating shaftand the central bearing.
 5. The assembly of claim 4, wherein thenutating shaft is configured to only nutate and not rotate substantiallywhen motor operates to rotate the rotating output shaft.
 6. The assemblyof claim 1, wherein the flexible seal includes a metal bellows.
 7. Theassembly of claim 6, wherein the metal bellows includes an electroformedmetal bellows.
 8. The assembly of claim 6, further comprising: a firstweld joint sealing an interface of the metal bellows and the sealedhousing; and a second weld joint sealing an interface of the metalbellows and the oscillating component.
 9. The assembly of claim 1,wherein the sealed housing and the flexible seal combine to form ahermetically sealed enclosure encasing the motor and the first coaxialshaft.
 10. The assembly of claim 1, further comprising a mechanicallyadjustable medical lead, the mechanically adjustable medical leadincluding a rotatable member mechanically connected to a distal end ofthe second coaxial shaft, wherein operation of the motor to rotate thesecond coaxial shaft rotates the rotatable member of the mechanicallyadjustable medical lead to move a position of an electrode of themechanically adjustable medical lead to adjust a spacing between aproximal end of the medical lead body and the electrode.
 11. Theassembly of claim 10, further comprising a force sensor configured tomeasure a resistance to movement of the position of the electrode anddeliver a force signal to a processor based on the resistance tomovement of the position of the electrode.
 12. The assembly of claim 1,further comprising a mechanically adjustable medical lead, themechanically adjustable medical lead including a rotatable membermechanically connected to a distal end of the second coaxial shaft,wherein operation of the motor to rotate the rotating output shaftrotates the rotatable member of the mechanically adjustable medical leadto move a radial orientation an electrode of the mechanically adjustablemedical lead.
 13. The assembly of claim 1, further comprising amechanically adjustable medical lead, the mechanically adjustablemedical lead including: an elongated medical lead body; a retractableelectrode located within a distal portion of the medical lead body; aninsulated conductor extending within the medical lead body, theinsulated conductor being in electrical contact with the electrode andextending to a proximal end of the medical lead body; and a rotatablemember positioned adjacent to the proximal end of the medical lead body,the rotatable member being mechanically connected to a distal end of thesecond coaxial shaft, wherein operation of the motor to rotate therotating output shaft rotates the rotatable member of the mechanicallyadjustable medical lead to move a position of the retractable electrodeto selectively deploy and retract the retractable electrode from themedical lead body.
 14. A method of adjusting a mechanically adjustablemedical lead, wherein the mechanically adjustable medical lead includesan electrode and a rotatable member, the rotatable member beingmechanically coupled to the electrode, the method comprising operating amotor within a hermetically sealed enclosure to drive the rotatablemember of the medical lead and move a position of the electrode toadjust a spacing between a proximal end of the medical lead and theelectrode.
 15. The method of claim 14, wherein the electrode ispositioned adjacent a distal end of the medical lead and rotation of therotatable member varies an overall length of the medical lead.
 16. Themethod of claim 15, further comprising measuring a resistance tomovement of the position of the electrode with a force sensor andoperating the motor to drive the rotatable member of the medical leadand move the position of the electrode based on the measured resistanceto movement of the position of the electrode.
 17. The method of claim14, wherein the mechanically adjustable medical lead further includes:an elongated medical lead body, wherein the electrode is located at adistal portion of the medical lead body and the rotatable memberpositioned adjacent to the proximal end of the medical lead body; and aninsulated conductor extending within the medical lead body, theinsulated conductor being in electrical contact with the electrode andextending to the proximal end of the medical lead body.
 18. The methodof claim 14, wherein the motor and the medical lead are part of anassembly, wherein the assembly further comprises: a sealed housing; amotor within the sealed housing, the motor including a rotating outputshaft; a first coaxial shaft within the sealed housing, the firstcoaxial shaft being mechanically coupled to the rotating output shaftsuch that rotation of the rotating output shaft drives rotation of thefirst coaxial shaft; a second coaxial shaft external to the sealedhousing, the second coaxial shaft being in axial alignment with thefirst coaxial shaft; an offset pin mechanically coupling the firstcoaxial shaft to the second coaxial shaft, wherein rotation of therotating first coaxial shaft drives a circular motion of the offset pinabout the axis of the first coaxial shaft, wherein the circular motionof the offset pin drives rotation of the second coaxial shaft; and aflexible seal including an oscillating cap, the oscillating cap beingmechanically coupled to the offset pin such that the oscillating caposcillates in unison with the circular motion of the offset pin, whereinthe sealed housing and the flexible seal combine to form thehermetically sealed enclosure encasing the motor and the first coaxialshaft.
 19. The method of claim 14, wherein the motor and the medicallead are part of an assembly, wherein the assembly further comprises: asealed housing, wherein the motor is within the sealed housing, themotor including a rotating output shaft; a nutating shaft, wherein aproximal end of the nutating shaft is coupled to the rotating outputshaft and within the sealed housing; a central bearing passing throughthe sealed housing and supporting a central portion of the nutatingshaft and within the sealed housing; and a flexible seal, a proximalside of the flexible seal covering a distal side of the central bearing,and a distal side of the flexible seal being secured to a distal portionof the nutating shaft located distally relative to the central bearing,wherein the sealed housing and the flexible seal combine to form thehermetically sealed enclosure encasing the motor, the rotating outputshaft, the proximal end of the nutating shaft and the central bearing.20. The method of claim 19, wherein flexible seal is substantially fixedto the sealed housing and the nutating shaft.